PART- 2 CHAPTER-6. Biology and Habitat Ecology of Channa aurantimaculata

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1 PART- 2 CHAPTER-6 Biology and Habitat Ecology of Channa aurantimaculata All the Asian snakehead species are assigned under the genus Channa Scopoli, 1777 and the African snakehead species Parachanna Teugels and Daget, Two new species of Channa were reported from Assam after a long span of time in the last part of 20 th century namely, Channa bleheri by Vierke, 1991 and Channa aurantimaculata by Musikasinthorn, 2000 prior to which there have been record of seven odd species in Assam. The new species Channa aurantimaculata was discovered by Musikasinthorn from his collection during a field survey in Dibrugarh, Assam commencing from 24th March to 15th April, Assam is considered as an important biodiversity hotspot sharing other three regions of Indian subcontinent - the Western Ghats, the Eastern Himalayas and the Western Himalayas (Rao, 1974; Kurup, 1974; Thirgood and Heath, 1994; Kottelat and Whitten, 1996). After careful investigations, the fish taxonomists have confessed that Channa species are still subject to confusion. The holotype of Channa aurantimaculata (KUMF 3135) described by Musikasinthorn from Dibrugarh was compared with the paratype collected from the same place (KUMF 3136, NSMT-P and; ZSI un -catalogued) that created the history of occurrence of the species from Assam. Thereafter, the ambiguity of the taxonomic status of the species has been removed and separated from two closely resembling species Channa barca and Channa stewartii. The literatures (Goswami et al., 2003, 2006; Vishwanath and Geetakumari, 2009) indicate that the species is endemic to the region. Indeed, the type locality of the species was not thoroughly investigated in other districts of the state. Keeping in view, the possible occurrence range of the species to northern part of the River Brahmaputra characterized by the environment of bounded tropical rain forest intercepted by riparian swamps was felt and accordingly a survey was conducted. This has led to the present investigation to confirm that distribution spectrum of the species ranges from Tinsukia- 58

2 Dibrugarh - Dhemaji - Lakhimpur. It is further reported that the species is extending its distribution to Arunachal Pradesh (Teju) (Vishwanath and Geeeta kumari, 2010), which is probably covering the border between easternmost part of Assam and Arunachal Pradesh. This orange spotted snakehead locally known as Naga cheng or Pakhara cheng is a priced food fish with ornamental importance. Among the other 8 species of the genus Channa aurantimaculata shares with Channa stewatii and Channa barca to live in holes or burrows. The present treatise has emphasized a detail study on Channa aurantimaculata in regard to its habitat structure, biometry, habitat ecology, biological attributes of length-weight relationship and condition factor, fecundity, pattern of scales, breeding performance and population density. Wide-ranging information of the Species Distribution range so far reported 1. P. Musikasinthorn, , Dibrugarh, Assam, Brahmaputra River basin, India. 2. M.M.Goswami, Arunav Borthakur and Janardan Pathak (2006) Dibrugarh and Tinsukia District of Assam, India. 3. W. Vishwanath and K.H. Geetakumari, Tezu river, Tezu district of Arunachal Pradesh, India Etymology Musikasinthorn, (2000) proposed the nomenclature of the species as follows: the naming of the species aurentimaculata was based on a Latin adjective adhered to the colouration of the fish with orange blotches (aurantium = orange, maculates = blotches) on side of the body. These blotches are distributed on side of the body of the fish. Synonymic status Considering all the literatures since the establishment of the species by Musikasinthorn (2000) no synonyms occurs in record (Walter et al., 2004); Calacademy.org.research/ Ichthyology/catalogue/24 January,

3 Common Name Orange spotted snake head (Musikasinthorn,2000). Local name The local name of the fish in Assam is Noga cheng in Dibrugarh and Tinsukia district of Assam and Pakhara cheng in Dhemaji and Lakhimpur district, Assam, India. Native range Endemic to middle Brahmaputra River basin, Northern Assam (Musikasinthorn, 2000). Extended native range Dibrugarh town, Dibrugarh, Assam; Tezu river, Tezu district, Arunachal Pradesh, India (Vishwanath and Geetakumari, 2010) and Dhemaji district in Northern part of Upper Brahmaputra River basin (present findings, 2014). Introduced range No introduction report so far. Size range Earlier report: To about 40 cm. Present record shows the size range of the species varying from 6.2 cm in fingerling to 41.4 cm in adult specimen Habitat preference As reported earlier (Walter et al., 2004) from forest streams, swamps and swamps adjacent to the Brahmaputra River in subtropical rain forest condition. Present study reveals that more suitable habitat is ranging from inundated riparian vegetation infested area to the microhabitat holes/burrows in the floor of riparian swamps adjacent to the tributaries/sub- tributaries/rivulets of the Brahmaputra River. Temperature range: Unknown except preferred habitat and known range is widely sub tropical (Walter et al., 2004). Present study reveals the temperature of the habitat as follows: 1. Microhabitat (holes/burrows): C 2. Artificial captive breeding cisterns: C 3. Open inundated water: C 60

4 ph range: No earlier record Present record shows in Microhabitat (holes/burrows) in Open inundated water Reproductive habits: No specific information, but probably a nest builder with pelagic egg like the majority of Channied fishes (Walter et al., 2004) Present findings as follows: 1. Breeds in inundated open area of riparian swamp 2. No specific record of nest breeding habit 3. Breeds naturally in captivity without building nests, pairing, nocturnal excitement (frequent jumping) during rains and artificial showering. Feeding range: No information, but more likely a carnivorous predator as adults (Walter et al., 2004). Present study reveals that the fish is a carnivorous predator mostly prefer plankton and mosquito larvae in larval stage up to fry, chopped earth worm and silk worm pupae in fingerling stage and earthworm, grasshopper, small fishes and frog in adult. Day time feeding and active nocturnal feeding hunting behaviour is noticed. Commercial importance in native range None known, (recently described species not listed on aquarist-oriented websites and unknown for sale in live food fish market, (Walter et al.,2004) Present findings: Known in Dhemaji and in surrounding region as highly priced food fish selling in the markets Listed as ornamental fish (Das and Biswas, 2008). Enters into aquaria culture locally by the pet fish hobbyist 61

5 Environmental concern Unknown; but probably a predator on other fishes and invertebrates (Walter et al., 2004). Present findings: Confirms as carnivore and active predator on fishes and other invertebrates with hunting behaviour. Since restricted to local distribution range of riparian zone and no wide range migration, more apparently there is an environmental concern for sustenance of its population in natural habitat. Conservation status Data deficient Channa aurantimaculata has a localized population and is only unknown from the type locality, but there is insufficient information on the species distribution and is assumed as data deficient (the IUCN Red List of Threatened Species, ) (http.// -24 Jan 2014). Present findings: The species is endemic to middle upper Brahmaputra River basin extending its distribution to both northern and southern banks. No report of occurrence of the species in lower Brahmaputra River basin (downstream valley) in Assam, India Biological aspects of the species The biological aspects of Channa aurantimaculata studied in this part (Part-2) of the thesis include the characteristic components such as- Biometry, Scale and colour patterns, Length- Weight relationship, and Condition factor, Fecundity, Gut analysis and Breeding Materials and Methods Biometric Study Measurement and counts were followed from Musikasinthorn (1998). The morphometric measurement for 24 parameters was done by using Mitutoyo Absolute Digimatic Dial Caliper (Japan), to the nearest 0.1mm. The morphometric measurements and meristic counts were done for confirmation of the species identification. The data were recorded to tenth of a centimeter. The parameters related to the body parts are tabulated as proportion of the standard length (SL) while the parameters related to the sub unit of head as proportion of the head length (HL). Fin ray counts were done by 62

6 using magnifying glass and binocular sterio-zoom microscope. The collected samples were preserved in 10 % formaldehyde solution. The literatures from the works of Menon (1974), Jayaram (1981), Sen (1985), Talwar and Jhingran (1991), Pandey and Sandhu (1992) and Musikasinthorn (2000), Vishwanath and Geetakumari (2009) were consulted for studying the biometric detail of the species. Study of Scales and Colour patterns Specimens for the present study were collected from Lachiachapari Riparian Wetland (LRWZ) zone during the period from The observations were made on the characters namely, large scales on both lower jaws, shield like scale on head, check scales, lateral line scale, scale below lateral line, circumpeduncular scales. The scale pattern and their arrangements on the body surface were studied following Lagler et al. (1977). The necessary photographs of the scales were taken by using digital camara. The colour pattern of the fish was studied in fresh living condition by observing band patterns, blotches and combination of black, white and orange colour on the surface of the body and fins following the work of Musikasinthorn ( 2000). Study of Length-Weight Relationship Length-Weight relationships of the species in male (sample size=15) and female (sample size= 27) were done separately following the formula of Le Cren (1951). A total of 42 specimens (15 male and 27 female ) with cumulative size ranges in TL and in BW of both sexes of Channa aurantimaculata were collected randomly from a riparian wetland namely Laciachapari beel (Longitude / 27 // E and Latitude / 33 // N ) of Dhemaji district of Assam during Nov, 2008 Oct, Since sex of the collected samples could not be distinguished by secondary sexual characters, all fishes were dissected and identified the sex based on gonadal structures following Mackie and Lewis (2001). The male specimens (15 number) and female specimens (27number) were separated for their length and weight. Total length (TL) were measured from tip of the snout to tip of the caudal fin nearest to 0.01 mm by using Mitutoyo Absolute Digimatic Dial Caliper (Japan) and Body weight (BW) of the fish samples were measured nearest to 0.01g by a digital balance individually. Lengthweight relationship were estimated by the equation W=a L b (Le Cren, 1951) which further expressed logarithmically as 63

7 Log W=Log a +b Log L Where, W= Weight of the fish, L=length of the fish and a and b are constant. Parameter a and b were calculated by the method of least square regression: Log a = log W. (log L) 2 - log L. (log L. log W) N. (log L) 2 ( log L) 2 Log b = Log W N. Log a Log L The value of correlation r, standard deviation (SD) between total length and body weight were calculated with the help of SPSS software (version-16) and Microsoft Office Excel. The Log transformed regression was used to test the growth. Relative condition factor ( Kn) was calculated as per Le Cren (1951) and is expressed as follows : Kn = W Ŵ Where W= observed weight, Ŵ= calculated weight derived from length-weight relationship. Study of Fecundity Total number of 30 samples of Channa aurantimaculata was collected from Lachiachapari wetland of Dhemaji district, Assam during breeding seasons in Total length (TL) and body weight (BW) was measured with the help of absolute digimatic dial caliper nearest to 0.01mm and digital electronic balance nearest to 0.01 g respectively. After sacrificing the fish the ovary weights (OW) were measured in digital balance (nearest to 0.01gm). For fecundity study one gram from the three cross sectional samples were taken from three position (anterior, middle and posterior) of the two lobes of each ovary and the pieces were kept in Gilson s fluid separately for 1 months to release the eggs. The total number of eggs in the entire ovary was calculated by multiplying the mean of the sub samples with total weight of the ovary. The Fecundity was studied following method suggested by Bagenal (1978).. F = S OW where, F= Fecundity, S= average no. of ova from three samples, OW = total weight of the ovary. 64

8 Gut content analysis Fresh samples of Channa aurantimaculata were collected to analyze the gut contents of the species. Availability of the small fishes were also collected from the open riparian zone of LARWZ to see the possible occurrence of the small fish species on which Channa aurantimaculata might feed. Seven numbers of freshly collected samples of Channa aurantimaculata were dissected and the guts were dissected out and preserved in 7% Formaldehyde. In the early morning samples the total gut with the stomachs were removed and cut open to examine the content. The qualitative analysis of the gut organisms were done based on the method put forwarded by Gahlawat et al.(2007). Study of Breeding : Natural & Ex-situ Three pairs of healthy matured live specimens of size ranges from cm in length were collected with utmost care from the holes/burrow of riparian swamp habitat of Lachiachapari riparian wetland zone (for rearing in cemented cistern. The specimens were acclimatized in three glass aquaria (one pair each) for 72 hours. Three cemented cisterns (6 / 4 / 3.5 / each) were prepared three months prior to introduction of the pairs. One pair ( and ) of the acclimatized fish was released into each cistern and cultured to raise as brooder by supplying live feed of earthworm, grasshopper, thrash fish and silkworm pupae. Healthy state of the fishes were monitored and found active throughout the culture. Chasing of female by the male was noticed during breeding three months of rearing. Showering of the cisterns was employed during this period of culture. After 6 days of chasing it was observed that spawning took place in two cisterns. It was observed that the male took part in active parental care. The physicochemical namely, ph, DO, FCO 2 and water temperature were analyzed following the same methods as described in Part-1,Chapter-3. Of the three cisterns it was found that the species bred in two cisterns successfully while it was not noticed in one cistern. The mortality of the larvae is monitored during the interval of 15 days, 30 days and 60 days. The captive breeding took place without injecting hormone. Breeding in Natural habitat was studies with the help of local fishers and skilled infringing inhabitants through physical observation and collection of spawn, fry and fingerling from the inundating riparian swamp zones during breeding flood season. Based on information from the local fishers field study were conducted from time to time. 65

9 Observations Biometry of Channa aurantimaculata Diagnostic Characteristics Body elongated, relatively slender; anterior portion of the body nearly circular, posterior portion nearly compressed; greatest body depth at the insertion of dorsal fin and greatest body width at insertion of pectoral fin; pectoral fin fan shaped with rounded margin and having a black blotch at base and 6-7 distinct orange bands vertically; pelvic fin short less than 50 % of pectoral fin length, not reaching anal fin; anal base long but shorter than the dorsal fin length; caudal fin rounded with 6-10 distinct vertical bands; dorsal fin elongated inserted mid-dorsally between the pectoral fins to the base of the caudal peduncle; 4-5 horizontal orange bands alternating 5 horizontal black bands in zigzag fashion; anal fin originating posterior to the vent equal to posterior end of the dorsal fin base vertically; caudal peduncle with 4 horizontal orange bands alternating black bands. Head elongated and flattened ventrally, inter-orbital region nearly flat, orbit below the dorsal contour of head from lateral view, patch of scales on gullar part absent. Mouth large with small conical teeth in premaxilla and additional series of larger conical teeth anteromedialy, a number of small teeth and 3 large conical teeth on prevomer, a row of conical teeth with 6-7 canines on each side of palatine, numerous small conical teeth on outer anterior region of dentary. Biometric attributes (Table-15) Dorsal profile of body straight from anterior to posterior, cylindrical and elongated where as ventral surface flattened from thorax to anal region, head conical snout rounded and like the head of a snake. The head length % SL, head depth % SL, body depth % SL, caudal peduncle length % SL, caudal peduncle height % SL, pre-dorsal length % SL, length of base of dorsal fin % SL, anal fin base length % SL, head width % HL, snout length % HL, eye diameter % HL (Table-15). 66

10 The meristic characteristic (Table-16) is presented by the count of dorsal fin rays 44-46, ventral fin rays 29-31, pectoral fin rays 15, pelvic fin rays 6, caudal fin rays 15 and 14. In life condition upper half of the body is dark brown to black with 8 to 9 large irregular orange blotches. Lower side of the body is yellow, golden or orange, becoming blue ventrally. Pectoral fin bears a black blotch at base, and 6 ventral broad vivid black bands. In 10% formaldehyde the live colour turns into light orange and dull bluish colour. Table 15: Morphometric study of Channa aurantimaculata (n =12) Standard length (SL) 39.6 (cm) (cm) % Standard length (SL) to % % Range Mean±SD Head length ±2.0 Head depth ± 0.9 Head width ±5.1 Body depth ±2.1 Body width ±5.0 Caudal peduncle length ±0.5 Caudal peduncle height ±0.4 Pre-dorsal length ±6.5 Post dorsal length ±1.9 Pre-pectoral length ±7.2 Pre-anal length ±18.3 Pre-ventral length ±10.6 Length of dorsal fin base ±8.9 Length of anal fin base ±24.8 Pectoral fin length ±2.8 Ventral fin length ±0.6 % Head length (HL) to Head depth ±4.5 Head width ±17.1 Snout length ±3.9 Inter orbital distance ±32.9 Eye diameter ±5.1 Upper jaw length ±19.6 Inter-orbital distance ±4.1 67

11 Table 16: Meristic characteristics of Channa aurantimaculata (n = 6). Meristic Parameters Numbers Dorsal fin rays 44(5), 46(1) Ventral fin rays 29 (4), 31(2) Pectoral fin rays 15 (6) Pelvic fin rays 6(6) Caudal fin rays 15(5), 14(1) Pre-dorsal scales 10 (4), 13(2) Lateral line scales 50(5), 53(1) Scale above lateral line 4.5(6) Scale below lateral line 9(4), 11(2) Circumpeduncular scale 24(3), 27(3) Scale between pre-opercular angle and posterior border of orbit 7(5), 9(1) Number of vertical bands on pectoral fin 7 (5), 6(1) Number of bands on body side(alternative dark and white) 13 (5), 14(1) Bands on dorsal fin 4(6) Bands on caudal fin 8 (6) Number of nasal bars 1(6) Number of Maxillary bars 0 (6) Number of mandibular 0(6) 68

12 Scales and Colour Pattern Scale Pattern (Photoplate- 5). Channa aurantimaculata, a species identified on the basis of colour pattern is morphologically unique species of murrels bearing both cycloid and ctenoid type of scales on the body, and some shield-like large cycloid scales on head that superficially resemble that of a snake. The cycloid scales are circular in outline with concentric line of growth (circluli). These scales are loosely arranged in the dermal pockets of the body (Figure. 5 & 6). On the other hand, the ctenoid scales remain seated obliquely. Their arrangements are found in such a manner that the posterior end of one scale overlap with the anterior edge other scale behind Outside the basal layer there lies the bony ridge layer that bears concentric ring i.e. circuli. The arrangement of circuli shows a great physiological importance in the species. During slower growth they normally placed close together each other. On the other hand circuli becomes heavy and fall apart during rapid growth period. The pattern and arrangement of scale in the studied specimens are explained belowi) Large Scales: 4-5 number of large shield like scales are found in the portion in between the two eyes (Photoplate- 5-A-h). This is one of the distinguishing characteristics of murrel species. Further, two cycloid scales are observed on each side of lower jaw under surface (Photoplate- 5-A- c-d). As earlier reports of Musikasinthorn (2000), this is one of the important characteristics of Channa aurantimaculata from which the species can be distinguished from other murrel species. ii) Cheek scales: These are also cycloid type of scales found to be arranged on either side of the check. Their number ranges from The scales associated with the lateral line as explained below are depicted in Photoplate-5-B. iii) Lateral line scales: The lateral line scales are of Ctenoid type. They form morphologically and physiologically important lateral line of the fish species. 69

13 The numbers of lateral line scales observed in the materials are iv) Scales above lateral line: These type of ctenoid scales are found to be arranged vertically in between lateral line and dorsal fin. The counted number of this scale is 4-5. v) Scale below lateral line: These ctenoid scales are arranged beneath the lateral line to the belly region. Their numbers observed are between vi) Circum-peduncular scale: These are cycloid type numbering in circum- penduncular region are vii) Scales between pre-opercular angle and posterior boarder of orbit: These are cycloid scales lying between the angle of the pre operculum and posterior edge of the orbit. Their number are counted as

14 Figure-5. Structure of Cycloid scale found in Channa aurantimaculata Figure-6. Structure of Ctenoid scale found in Channa aurantimaculata Colour Pattern (Photoplate-6 & 7) 1. Eight to nine V shaped black blotches from the dorso- lateral half of the lateral surface area alternating with eight to nine inverted V shaped yellow blotches from the ventro lateral half of the lateral surface of the body extending from behind the origin of dorsal fin to the caudal peduncle. Several tiny orange irregular spots and black irregular spota are distributed on the black blotches and yellow blotches respectively. 71

15 2. Lower lateral side of the body yellow or golden and black in ventral surface. 3. Nine black vertical bands are alternating eight yellow vertical bands intermingle with orange tinge in pectoral fin in completely matured fish. At the base of the pectoral fin two small blotches appear during fully matured specimen. 4. Anal fin rays are bluish green. The base is lined by broken scattered lining of a band below which three dotted lines lie parallel below over the rays on the bluish green membrane. 5. Pelvic fin rays are yellow to gray upon white membrane with alternating 3-4 black and yellow bands. 6. Elongated dorsal fin is brightly colored with 5-6 alternate horizontal broken orange bands with broken black bands peculiarly arranged in irregularly intercepted manner to each other. 7. Fan shaped caudal fin with 7 distinct black bands alternated by 8 golden/orange bands, two (1 in base and 1 in tip) of which are indistinctly noticed. The fin rays are distinctly orange in color. 8. Each scale of the head region is lined by its margin with orange lining and centrally black. The opercular part is olive green in color. Lower lateral portion of operculum is orange to yellow while the ventral side of the head is whitish with many small to medium irregular black blotches. In the formalin preserved sample all orange of yellow or golden colours appear pale white while greenish or bluish colour disappears to remain as gray colour. Larval colouration: The spawns are ash coloured, black spots appear in fingerling stage (two months larva) followed by yellowish vertical bands in ventro-lateral side of body. Light yellow bands are visible in pectoral fin in fingerling stage. There after characteristic colour starts to appear in the line of the adult. 72

16 Length-Weight Relationship and Condition Factor The present investigation deals with computing the length - weight relationship, condition factor and relative condition factor of Channa aurantimaculata from the natural stock of Lachiachapari riparian wetland zone (LRWZ). Length-weight relationship, condition factor and relative condition factor of the species have been evaluated during the feeding cycle (December - March/April) in the year November 2008 to October The relative growth coefficient (b) values of male is found to be 4.18 and for female is 2.65, the condition factor (K) value is 1.29 ± 0.27 of male and 1.66 ± 0.28 of female, relative condition factor (Kn) value 1.05 ± 0.42 in male and 1.00 ± 0.40 in female are observed. The coefficient of correlation (r ) in both the sexes exhibit allometric growth (negative in female (Table-18) and highly positive in male ( Table -17). In the present study the body weight of male and female have been ranged between and g and and g respectively and the total length between 28.2 and 39.6 cm in male and 21.4 and 38.9 cm in female. The value of a, b, r and mean ± SD of male and female are given in the Table- 19. The K and Kn values are depicted in Table- 20. The regression graphs of LWR and condition factor (K) are depicted in Figure- 7 & Figure- 8. Logarithmic form of Length- weight relationship is expressed by the following equations for male and females as For Male: Log W = Log L For Female: Log W = Log L 73

17 Table-17. Length and Weight measurement of Channa aurantimaculata ( male population) in Laciachapari riparian wetland zone (LRWZ) SL No. TL (cm) Log TL Log TL. Log TL BW(g) Log BW Log TL x Log BW

18 Table-18. Length and Weight of Channa aurantimaculata (female population) in Laciachapari riparian wetland zone (LRWZ) SL No. TL (cm) Log TL Log TL 2 BW(g) Log BW Log BW x Log TL

19 Table- 19: Correlation coefficient ( r ) between Length(TL) and Weight (BW) of Channa aurantimaculata in male and female population Sex Male N=15 Female N=27 Weight range Size range Mean±SD BW Mean±SD TL Value of (g) (cm) (g) (cm) a Value of r b value ± ± ± ± Table. 20: Condition factor (K) and Relative condition factor (Kn) of Channa aurantimaculata in male and female population Sex Weight range (gm) Size range (cm) Range of K Range of Kn Mean ± SD K-value Mean ± SD Kn Male N= ± ± 0.42 Female N= ± ±

20 A B Figure -7. Length-weight relationship of Channa aurantimaculata in male and Female population C D Figure - 8. Condition factor (Kn) in relation to body weight (g) of Channa aurantimaculata in C- male and D-female population. 77

21 Study of Fecundity Fecundity is considered as one of the essential and most important biological parameter of a fish species. The number of eggs contained in the ovary of a fish is termed as fecundity (Nikolsky, 1963). An adequate knowledge of the fecundity of fish is most essential for evaluating the commercial potential, stock study, life history, practical culture and actual management of the fishery (Lagler et al., 1956; Doha and Hye, 1970). Study of fecundity in fishes is basically important for their successful culture and effective management (Mian and Dewan, 1984) and it is also necessary to determine the index of density dependent factor affecting population size (Simpson, 1951). In the present study the fecundity (F), total length (TL), body weight (BW) and ovary weight (OW) of Channa aurantimaculata have ranged between , cm, g and g respectively. The value of r and mean ± SD of F, TL, BW and OW were given in the Tables- 21 & 22. The regression graph of Log F with Log TL, Log BW and Log OW are depicted in Figures- 9 (a) (c). 78

22 Table-21. Fecundity relationship to Total length (TL), Body weight (BW) and Ovary weight (OW) of Channa aurantimaculata Sl. No. Facundity (F) Log F TL LogTL BW Log BW OW Log OW

23 Table-22. Correlation-coefficient of fecundity to body weight, total length and ovary weight in Channa aurantimaculata Fecundity ( ) ( ± ) N=30 Body parameters Range Mean±SD Value of ' r ' ** Correlation is significant at the 0.01 level (2-tailed) TL (cm) ± ** BW (g) ± ** OW (g) ± ** (a (b) (c) Figure - 9. Relationship of Fecundity (Log F) with Total length (Log TL), Body weight (Log BW) and Ovary weight (Log OW) (a= Log F with Log TL, b=log F with Log BW; c= Log F with Log OW) of Channa aurantimaculata 80

24 Gut analysis for determination of feed pattern A study is conducted in LARWZ during flood inundation in to identity the small fishes in the habitat. The fish samples are collected of the habitat to observe the availability of feed fishes of the species up to the species level (Table 23). Altogether forty one small fishes are recorded in the fully inundated period from the studied wetland habitat during the fishing period. Table-23: Gut content analysis showing piscine and non piscine organism available in the gut of Channa aurantimaculata SL No. Fish species S1 S2 S3 S4 S5 S6 S7 1 Amblypharygodon mola Badis sp Chanda sp Channa punctata Channa gachua Chela sp Trichogaster sp Labeo bata Lepidocephalus sp Mystus sp Puntius sp Piruliosona sp Esomus dendicus Salmostoma bachila Unidentified fishes Non piscine organisms 16 Macrobrachium Grass hopper Dragonfly nymph Unidentified organic mass

25 Breeding Activity Breeding in Natural habitat ( Photoplate-8) In the natural environment the study was conducted to determine the feeding and breeding pattern of Channa aurantimaculata. During the flood season all the riparian swamps in Lachiachapari wetland zone and Lambachapari wetland zone receive river water to get inundated up to a water depth of about one meter of the read swamp vegetation. The fishes to come out of their respective holes to perform active feeding on small fishes during the non- breeding phase. Taking the advantage of active feeding period the fishes prepare to enter into the breeding phase in pairs. Spawning starts in the monsoon (April-June). Spawn and larval forms starts active feeding in the inundated swamps to grow vigorously to attain a fingerling stage. Parental care is visibly noticed during that period. After active feeding, the fingerling sustain the growth period to attain a pre-juvenile stage. After the first flood (receding of flood water) a second flood is experienced by the swamp habitat which again activates the adult fish to be prepared for the second phase of breeding in nature during post monsoon to early part of retreating monsoon (July-September). Within this period the species breed for second time following the same pattern of breeding cycle. After the retreating monsoon the commencement of dry season starts and the total water of the swamps completed the flood cycle to enter into the winter dry season. All the adults start selection of holes in pairs followed by the juveniles to undergo a hibernation period in holes throughout the dry winter period lasting for 5-6 months (December to March). The same life cycle is followed by the adults in the following year and inherently by the juveniles. After examination of the breeding pattern of the species in open natural environment an ex-situ breeding trial is done in cistern to determine the captive breeding of the fish(. Only one phase of breeding cycle is observed to determine some specific reproductive behaviour of the fish. Ex-situ Breeding (Photoplate-9) From the present study it is observed that the cistern introduced individuals initially are quite reluctant to feed on supplied feed items. However, eight days onwards from introduction they begin to perform normal feeding behavior (Photoplate-10). Among all the food materials supplied, the fishes prefer to feed on earthworm (60 %) followed by insects (40 %). Surprisingly except earthworm and 82

26 silkworm pupae they do not prefer any dead animal or even fish. Intaking of food is noticed mostly during the day hours. However, nocturnal feeding is also observed occasionally. Frequent nocturnal jumping of the brooders are noticed just before matting. The artificial showering seem to stimulate the matting in captive environmental condition. The fry of Channa aurantimaculata are nearly similar to the fry of Channa punctata and Channa striata, but after the fingerling stage black spots appear in the ventro-lateral side supplemented by yellowish vertical strips. A black and yellow coloration is also observed in the caudal, dorsal, pectoral and anal fins. Gonadal maturity is marked by appearance of a black blotch at the base of pectoral fin. Adult male and female fishes show little sexual differences. The male is slightly slender, more dazzling and it bears yellow reticulation on scales in comparison to the female. This species produces maximum 350 offsprings were in cistern. It is observed that during first 15 days larvae feed on planktonic food only. After the breeding, 97 numbers of fry are reared in the glass aquarium to study their feeding behaviour. After 15 days the fry (size cm) fed on mosquito larvae. It is observed that a single fry can consume as many as mosquito larvae within an hour. The fingerlings are supplied with chopped earthworm only and reared up to the size of cm in length and g in weight. The mortality rate is observed to be below five percent (Table 25). The ex-situ breeding trial it is evident that Channa aurantimaculata can be reared and bred in captive habitat. The basic necessity of the water quality in cistern during breeding is noticed. The optimal temperature range remains at C, ph between , Dissolved oxygen between mg.l -1 and Free Carbon dioxide between mg.l -1 (Table- 24). 83

27 Table 24. Some Physico-chemical water parameters of breeding cistern Month Temperature( 0 C) ph Dissolved oxygen (mg.l -1 ) Free Carbondioxide(mg.l -1 ) March April June Table 25. Growth and survival of Channa aurantimaculta in cistern Age of the Fish Average length (cm) Average weight (g) Type of food 15 days Mosquito larvae and plankton 30 days Mosquito larvae 60 days Chopped earthworm, silkworm pupae Mortality rate 2% 1.5% 1% 84

28 6.2. HABITAT ECOLOGY Habitat structures of Channa aurantimaculta The study for habitat structure of the species was conducted in two specific habitat territories within the district, namely Lambachapari(LAMRWZ) and Laciachapari riparian wetland zones(lrwz). The entire coverage zone bears the characteristics of shallow water depression, which remains submerged during the rainy seasons and subsequently dry up during winter seasons. This specific characteristic of the entire habitat zones can be distinguished into two remarkable categories (i) Inundated storage water area (ii) wet exposed bottom mud area. The studied fish species utilize the full storage water area as open inundating habitat zone for its free swimming foraging life that includes growth, development and breeding. On the other hand, the exposed wet bottom mud area is used as nonbreeding hibernating phase (microhabitat) of its life cycle. Materials and method The habitat ecology study was carried out during February, 2008 to January, Open inundated habitat zone was observed during rainy season with the help of local inhabitant fishers. The foraging and breeding life of the fish were studied based on information and identification on the spots. For study of microhabitat, physical survey for verification of the holes/burrows was conducted during dry seasons (October February). The holes were identified with the help of local catcher and skilled hunter on the fish using their traditional methods. All together twenty holes from each riparian zones were studied to dug out the fishes, which was done for the population study (Table 29, 30 & 31).Twenty nine live specimen of Channa aurantimaculata (male and female) from hibernating stage were collected. The collected specimens were studied in the live condition and preserved in 10 % formaldehyde solution for further study. The supporting photographs of riparian zone and microhabitat were taken on the spot. The microhabitat structure and physical verification of burrows or holes were done during dry seasons after identifying the habitat locality of the species in riparian swamps. After excavating the holes a microhabitat design was constructed 85

29 (Photoplate-10). For study of microhabitat, the physical survey was conducted during dry seasons (October February). The holes were identified with the help of local catcher and skilled hunter on the fish using their traditional methods. Altogether twenty holes from each riparian zones were studied to dig out the fishes, which was done for the population study (Table 29, 30 & 31). Methodology for vegetation study A qualitative study of the dominant macrophytic cover was made in the riparian swamps considered as the habitat of C. aurantimaculata based on random collection of swamp vegetation by The dominant macrophytes were collected by belt transect with 5m 2 intersections. The macrophytes are identified following Kaul and Zutshi (1967) and by comparing with the herbarium sheets in the laboratory of Botany Department, Dhemaji College. Methodology for Population study The population study of the species was conducted in four randomly selected swamps covering a total area of 7.5 Km 2. in LRWZ while in LMBRWZ it was worked out in four swamps with a total area coverage of Km 2. Quadrate method was employed to count the number of microhabitat (Figure.- ) taking into consideration 10 m 2 (0.01 Km 2 ) quadrate area in each operation in both the habitat zones (Table 31). 10 numbers of hole /burrow (microhabitat) each in LRWZ and LMBRWZ covering four riparian swamp habitats were excavated (Photo plate 11) to determine the standard population per hole/burrow (microhabitat). To calculate the total population 6 such operations in each swamp were conducted ie 10 m 2 (0.01 Km 2 ) x 6 operation in each swamp (Table 30). Normally one pair (1 male and 1 female) of the species hibernates inside each hole unless caught or disturbed. Therefore, this standard population estimation is applicable to the population estimation of the entire riparian zones in LRWZ and LAMRWZ. 86

30 Microhabitat study Observations The present study reveals that the microhabitat of Channa aurantimaculta is confined to its non- breeding or hibernating phase of life cycle. The holes are exposed in the wet muddy surface (Photoplate-11& 12) inside the area covered by thick tall riparian reed vegetations (Photoplate-13). A diagrammatic illustration is presented to show the structure of the microhabitat holes (Photoplate-10). For each pair (male and female) of the species two holes are noticed on the surface, which are connected to form a vertical tunnel under muddy surface that lead to form two hollows expanded bulbs. The submerged holes follow the water table and contain fresh clear water. The maximum depth of the entire microhabitat varies from cm, the mouth of the holes from cm depth of two surface holes to their submerged joining point cm and two chambered bulb area expanding to their breadth cm. Both the bulbs are inter-connected by a narrow tube. The chamber used by the female is larger than the chamber used by the male. Since the female is more bulky in size, probably they use the larger chamber. That the holes contain the fish can be identified on the basis of the occasional turbidity of the water in the hole mouth which is due to gulping of the fish to take air from time to time. The holes that do not contain the fish show clear transparent water in the mouth of the holes. Information gathered about the traditional fishing methods used by the catchers that they place a special type of bamboo trap in the mouth of the turbid hole and as soon as the fish jump to the hole surface for gulping air they are trapped in the device. Vegetational Pattern The entire riparian habitat zones are covered by Phragmites karka (Nol khagari), which is thickly populated over the wet muddy soil surface leveling the height of about cm. The healthy patches of the vegetation in the central part indicate occurrence of more holes than the area covered by thinly populated patches of vegetation. The other intermingled vegetation in the habitat zone are Cyclosorus gangylodes (Ban Dhekia) and Clinogyne dichotoma (Patidoi), which follows the dominance of Phragmites karka. 87

31 Physico-chemical quality of the holes Physico-chemical parameters namely temperature, ph, dissolved oxygen (DO), free carbon dioxide (FCO 2 ), total hardness (TH), total alkalinity (carbonate alkalinity), nitrate-nitrogen, ammonical nitrogen and phosphate were studied in the hole water and temperature and ph in the submerged soil of the holes. The water parameters were studied by using using Chemical Analyzing Kit (Aquamerck-11151) and the soil temperature was measured on the spot (sediment in the microhabitat holes) by using soil thermometer while the soil ph was measured Ecoscan Digital Meter after preparation of the suspension (1:10) of sediment w/v in distilled water. The hole water colder with temperature remaining within a range of ( o C), ph acidic ( ), DO of moderate range ( mg. l -1 ), FCO 2 in trace (0-.3 mg. l -1 ), Bicabonate alkalinity nil & poor carbonate alkalinity ( mg. l -1 ), presence of Phosphate (mg. l -1 ) and Nitrite nitrogen (mg. l -1 ) -(Table -26). At the same time soil temperature of the holes is significantly lower than the hole water temperature ( o C vs o C) and the ph is more acidic ( vs ) - Table -27. Table-26: Physico-chemical parameters of water and soil in microhabitat holes of Channa aurantimaculata. SL No. Parameter (Hole water) Range 1 Temperature ( o C) ph Dissolved oxygen (mg. l -1) Free carbon dioxide(mg. l -1) Bicarbonate alkalinity (mg. l -1 ) nil 6 Carbonate alkalinity (mg. l -1 ) Nitrate nitrogen NO3-N (mg. l -1 ) Nitrite nitrogen NO2-N (mg. l -1 ) Phosphate (mg. l -1 ) Soil from hole 1 Temperature ( 0 C) ph

32 Inundated habitat Zone All the studied riparian swamps undergo flood inundation phase (April/May September/October) in the same territory in which the holes are located during the dry season. The careful habitat study indicates that after recovery of the hibernation period the fishes come out of the holes to the over ground inundated area of the riparian swamps for foraging and breeding and enjoy a free living life of the two studied zones (LAMRWZ and LRWZ), the Lambachapari riparian wetland zone (LAMRWZ) is situated in the western bank of river Lali in the greater Lamba chapori and fed by the same river during flood inundation. The other studied riparian swamp is Lachia chapori riparian wetland zone also constituted by the same territorial condition set up. This studied is situated in the western bank of Lachia sub-tributary of Gainadi river tributary at a distance 5 km south east of Dhemaji town, which is fed by flood inundated water of Lachia river. This hole dwelling fish after over coming the hole dwelling hibernation period enjoy a free living life in the inundated riparian swamps for foraging and breeding. The flood inundated period for free living phase of the fish is about 5-6 months depending upon the flood situation of the rivers. It is observed during the habitat territorial study that there are number of shallow depressions inside the thickly populated vegetation area of Phragmites karka which are seems to be ideal breeding ground of fishes during flood receding period. The fishes found to forage on tiny fishes (Table 28) in the area which are studied during fish catches in the depressions. 89

33 Table-28: Occurrence of small fish species along with the Channa species in LRWZ habitat based on fishing during the inundation period. SL No. Fishes SL No. Fishes 1 Gadusia chapra 22 Heteropneustis fossilis 2 Notopterus notopterus 23 Gagata gagata 3 Chela cachius 24 Xenetodon cancila 4 Laubuca caeruleostigmata 25 Channa gachua 5 Salmophasia bacaila 26 Channa punctate 6 Esomus danricus 27 Channa aurantimaculata 7 Resbora daniconius 28 Channa striata 8 Amblypharygodon mola 29 Channa marulius 9 Cabdio morar 30 Channa stewartii 10 Labeo bata 31 Chanda nama 11 Puntius chola 32 Pseudoambassis ranga 12 Puntius sophore 33 Parambassis lala 13 Pethia gelius 34 Badis badis 14 Puntius ticto 35 Nandus nandus 15 Lepidocephalichthys 36 Glossogobius giuris 16 Botia Dario 37 Anabus testudineus 17 Mystus bleekeri 38 Tricogaster fasciata 18 M. vittatus 39 Tricogaster lalius 19 Ompok bimaculatus 40 Tricogaster cuna 20 Neotropius atherinoides 41 Macrognathus pancalus 21 Clarias magur 42 Macrognathus aral 90

34 Population density of Channa aurantimaculata Study reveals that Channa aurantimaculata is found to be abundant in the riparian habitat zones of Dhemaji district. Two different riparian zones (Photo plate 10) are identified, namely Lacia chapori Riparioan Wetland Zone (LRWZ) and Lamba chapori Riparioan Wetland Zone (LAMRWZ). The LARWZ comprises 13 riparian swamps (unnamed) and LAMRWZ is composed of 8 riparian swamps of which 4 are named as Lamba chapori, Apsara chapori, Ahamia chapori and Mising chapori. The total riparian area of the LRWZ, which is fed by Lachia sub tributary is Km 2 and the LAMRWZ Km 2, fed by Lali river tributary of the Brahmaputra River (Table 29). The population study of the species was conducted in four randomly selected swamps covering a total area of 7.5 Km 2. in LRWZ while in LAMRWZ it was worked out in four swamps with a total area coverage of Km 2. Quadrate method was employed to count the number of microhabitat (Figure.- ) taking into consideration 10 m 2 (0.01 Km 2 ) quadrate area in each operation in both the habitat zones (Table 31). 10 numbers of hole /burrow (microhabitat) each in LRWZ and LAMRWZ covering four riparian swamp habitats were excavated (Photo plate 11) to determine the standard population per hole/burrow (microhabitat). To calculate the total population 6 such operations in each swamp were conducted ie 10 m 2 (0.01 Km 2 ) x 6 operation in each swamp (Table 30). Normally one pair (1 male and 1 female) of the species hibernates inside each hole unless caught or disturbed. Therefore, this standard population estimation is applicable to the population estimation of the entire riparian zones in LRWZ and LAMRWZ. 91