NSave Nature to Survive

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1 ISSN: NSave Nature to Survive : Special issue, Vol. III: ; 2013 AN INTERNATIONAL QUARTERLY JOURNAL OF ENVIRONMENTAL SCIENCES DIVERSITY, ABUNDANCE AND HABITAT STUDY OF LARVIVOROUS FISHES IN URBAN AREAS OF NALBARI DISTRICT, ASSAM Hitesh Das and Amalesh Dutta KEYWORDS Diversity Larvivorous fishes Nalbari Assam Prof. P. C. Mishra Felicitation Volume Paper presented in National Seminar on Ecology, Environment & Development January, 2013 organised by Deptt. of Environmental Sciences, Sambalpur University, Sambalpur Guest Editors: S. K. Sahu, S. K. Pattanayak and M. R. Mahananda 377

2 NSave Nature to Survive QUARTERLY HITESH DAS* AND AMALESH DUTTA Department of Zoology, Gauhati University, Guwahati hiteshdas11@gmail.com ABSTRACT Both indigenous and exotic fishes are used as biological control agents of mosquitoes throughout the country. Such mosquito larvae eating fishes are found in all types of freshwater habitats. A study was conducted to assess the relative abundance, diversity and habitat of these fishes from different aquatic habitats like ponds, wetlands, irrigation canal etc. of Nalbari town area of Nalbari district during During survey period altogether 21 species of larvivorous fishes belongs to 15 genera, 11 families and 5 orders were observed. Present study indicates that order Perciformes contributes highest and Osteoglossiformes along with Siluriformes contributes lowest species composition. Among these fishes Channa gachua was the dominant species found from all types of habitats, while Puntius sp. and Notopterus notopterus were collected higher from only those habitats with high dissolved oxygen content (6.8 ± ± 0.04 mg/l). INTRODUCTION Larvivorous fish are those that feed on immature stages of mosquitoes. According to Job (1940), larvivorous fish must be small, hardy and capable of getting about easily in shallow waters among thick weeds where mosquitoes find suitable breeding grounds. They must be drought resistant and capable of flourishing in both deep and shallow waters as well as living in drinking water tanks and pools without contaminating the water. They must have the ability to withstand rough handling and transportation for long distances. Larvivorous fish must be prolific breeders having shorter span of life cycle. They must breed freely and successfully in confined waters. Larvivorous fish should be surface feeders and carnivorous in habit and should have a predilection for mosquito larvae even in the presence of other food materials. Another important criterion of all larvivorous species should be its appearance. They should not be brightly coloured or attractive. They should be compatible with the existing fish life in that environment. Above all, they should have no food value, so that the fish-eating people discard them. The use of fish for controlling mosquitoes was an important tool in the pre-ddt era (Floore, 2006; Walker and Lynch, 2007). Typically fish were introduced into all potential mosquito breeding habitats, including rice fields, marshes, dams, canals and ponds (Hadjinicolaou and Betzios, 1973; Motabar, 1978). Biological control, particularly using larvivorous fish, was important to malaria control programmes in the 20 th century, particularly in urban and periurban areas for immediate use in developed and developing countries (Gratz and Pal, 1998). It has a very positive role to play in the integrated control methodologies in which both pesticides and fish or other biotic agents have their own roles (Mulla, 1961). Biological control refers to the introduction or manipulation of organisms to suppress vector populations. A wide range of organisms helps to regulate mosquito populations naturally through predation, parasitism and competition. As biological mosquito control agents, larvivorous fish (i.e., those that feed on immature stages of mosquitoes) are being used extensively all over the world since the early 1900s (pre DDT era) (Raghavendra and Subbarao, 2002). There was no significant work done on larvivorous fishes from Assam. Only single reference is documented in this respect from the work of Sheikh et al. (1991). The urban areas of Nalbari town generally not regarded as a malaria dominant zone, but in previous years Anopheles minimus, a common species among malaria vector mosquitoes was reported from this area (Prakash et al., 1995). Therefore present work was attempt to study on the Nalbari town of Nalbari district, Assam. MATERIALS AND METHODS *Corresponding author Study area The Nalbari town is the head quarter of Nalbari district. It lies between 26º44/N latitude to 91º44/E longitude. There are diversified aquatic habitats such as ponds, marshy wetlands; irrigation canals etc. are located in urban areas of this town. 378

3 LARVIVOROUS FISHES OF NALBARI DISTRICT, ASSAM Table1: Seasonal availability of fish species in urban areas of Nabari district TaxonomicPosition Name of the species PM (N ) M (N) RM(N) W(N) Osteoglossiformes Notopteridae Notopterus notopterus (Pallas) Cypriniformes Cyprinidae Amblypharygodon mola (Hamilton-Buchanan) Rasbora daniconius (Hamilton) Esomus danrica (Hamilton) Puntius sophore (Hamilton) P. ticto (Hamilton) Perciformes Ambassidae Chanda nama (Hamilton) Pseudambassis ranga (Hamilton) Anabantidae Anabus testudenius (Bloch) Cichlidae Oreochromis mossambicus (Peters) Osphronemidae Trichogaster fasciatus (Schneider) T. chuna (Hamilton- Buchanan) T. lalius (Hamilton- Buchanan) Channidae Channa gachua (Bloch- Schneider) C. punctata (Bloch) C. stewartii (Playfair) C. striata (Bloch) Gobiidae Glossogobius giuris (Hamilton- Buchanan) Siluriformes Bagridae Mustus vittatus (Bloch) Cyprinodontiformes Aplochelidae Aplocheilus panchax (Hamilton) Poecilidae Gambusia affinis (Baird and Girard) Note- PM= Pre-monsoon, M= Monsoon, RM= Retreating monsoon, W= winter, N=Number of fish species Sampling of fish Fish samples were collected during the period of in four different seasons viz., pre-monsoon (March-May), monsoon (June-September), retreating monsoon (October- November) and winter (December-February) after Borthakur (1986).Sampling was done from the study site with the help of cast net, dip net, local bamboo traps and hooks etc. The fish samples were preserved in 5% aqueous formalin solution (v/ v) directly. Identification Identification of collected fish samples were done after Jayaram (1999), Talwar and Jhingran (1991), Nath and Dey (2000). The latest scientific names of the fish species were followed after the website www. Calacademy. org/res/ ichthyo/ catalogue. Diversity indices Species diversity of ichthyofauna was estimated using Shannon-Weiner index (H) after Shannon-Weiner (1949) and Evenness index (E) was estimated following Pielou (1966). Dominance status of various species was described on the basis of relative abundance following Engelmann s scale (Engelmann, 1973). Habitat Study The habitat study of larvivorous fishes was carried out on the basis of both primary and secondary data. The primary data were collected from the field through survey and spot observation. Secondary data were collected through observation and interview with the fishers through questionnaire. More over habitat of each species was traced by means of tolerance level of dissolved oxygen in each type of habitat. Sampling of water The water samples were collected during the period of in monthly intervals. Dissolved oxygen analysis was performed at the sites by Winkler s modified technique according to APHA (1998). RESULTS AND DISCUSSION A total of 21 species of larvivorous fishes belong to 5 orders, 11 families and 15 genera have been recorded from the urban areas of Nalbari district during the study period. The fish species of these areas belong to the following five orders- 379

4 HITESH DAS AND AMALESH DUTTA Table 2: Dominant status of different fish species in urban areas of Nabari district TaxonomicPosition Name of the species Number Relative Dominancestatus abundance (R A) % Osteoglossiformes Notopteridae Notopterus notopterus (Pallas) Recedent Cypriniformes Cyprinidae Amblypharygodon mola (Hamilton-Buchanan) Subdominant Rasbora daniconius (Hamilton) Recedent Esomus danrica (Hamilton) Subdominant Puntius sophore (Hamilton) Subdominant P. ticto (Hamilton) Recedent Perciformes Ambassidae Chanda nama (Hamilton) Subdominant Pseudambassis ranga (Hamilton) Subdominant Anabantidae Anabus testudenius (Bloch) Recedent Cichlidae Oreochromis mossambicus (Peters) Subdominant Belontiidae Trichogaster fasciatus (Schneider) Subdominant T. chuna (Hamilton- Buchanan) Subdominant T. lalius (Hamilton- Buchanan) Subdominant Channidae Channa gachua (Bloch- Schneider) Dominant C. punctata (Bloch) Subdominant C. stewartii (Playfair) Recedent C. striata (Bloch) Recedent Gobiidae Glossogobius giuris (Hamilton- Buchanan) Recedent Siluriformes Bagridae Mustus vittatus (Bloch) Subdominant Cyprinodontiformes Aplochelidae Aplocheilus panchax (Hamilton) Subdominant Poecilidae Gambusia affinis (Baird and Girard) Subdominant RA<1% = Subrecedent; % = Recedent; %= Subdominant; = Dominant; > 31.7 % = Eudominant (Engelmann, 1973) Table 3: Seasonal variation in species abundance, species richness, species diversity and evenness of fish species in urban areas of Nabari district Seasons Pre-monsoon Monsoon Retreating monsoon Winter Number of individuals (N)(Species Abundance) Number of species (Richness) Species diversity (H) Evenness (E) Table 4: Different types of habitat of larvivorous fishes with dissolved oxygen level Habitat Type Dissolved Oxygen (mg/l) Pond (P) 8.6 ± 0.04 Marshy Wetlands (MW) 5.9 ± 0.20 Deep Irrigation Canals (DIC) 6.8 ± 0.21 Shallow Irrigation Canals (SIC) 4.5 ± 0.18 Rivulets (R) 7.2 ± 0.11 Crop Fields (CF) 5.8 ± 0.30 Osteoglossiformes, Cypriniformes, Siluriformes, Perciformes and Cyprinodontiformes. Out of these 21 species, 5 belong to family Cyprinidae, followed by Channidae (4), Osphronemidae (3), Ambassidae (2), Notopteridae (1), Anabantidae (1), Cichlidae (1), Gobiidae (1), Bagridae (1), Aplocheilidae (1), and Poecilidae (1). The collected fish species from different types of habitats of Nalbari town are depicted in Table 1. Among all the orders of fish fauna Cypriniformes were found to be the order with highest species composition (56%) and order Osteoglossiformes along with Cyprinodontiformes with lowest species composition (5%) respectively. Among these species, 11 species assessed as subdominant, 7 as recedent category and 1 species as dominant category. Channa gachua (Bloch- Schneider) was the highest dominant (RA %) and Channa striata (Bloch) (RA-1.78 %) was the least dominant species. All the larvivorous fish species with their dominance status plotted in Table 2. Species abundance found maximum during monsoon and minimum during winter. Species richness noted equal in all seasons. Species diversity (H) estimated maximum during pre-monsoon and minimum during retreating monsoon. Evenness observed maximum during pre-monsoon and minimum during 380

5 LARVIVOROUS FISHES OF NALBARI DISTRICT, ASSAM Table 5: Habitat types of larvivorous fish species in urban areas of Nabari district Name of the species P MW DIC SIC R CF Notopterus notopterus (Pallas) Amblypharygodon mola Rasbora daniconius (Hamilton) Esomus danrica (Hamilton) Puntius sophore (Hamilton) P. ticto (Hamilton) Chanda nama (Hamilton) Pseudambassis ranga (Hamilton) Anabus testudenius (Bloch) Oreochromis mossambicus (Peters) Trichogaster fasciatus (Schneider) T. chuna (Hamilton- Buchanan) T. lalius (Hamilton- Buchanan) Channa gachua (Bloch- Schneider) C. punctata (Bloch) C. stewartii (Playfair) C. striata (Bloch) Glossogobius giuris (Hamilton- Buchanan) Mustus vittatus (Bloch) Aplocheilus panchax (Hamilton) Gambusia affinis (Baird and Girard) Note: + = present; - = absent Osteoglossiformes Cypriniformes Perciformes Siluriformes Cyprinodontiformes Recedent Subdominant Dominant Figure 1: Larvivorous fish species of urban areas of Nalbati Town (% per order) retreating monsoon. All the results regarding diversity and abundance of larvivorous fish species of Nalbari town area are depicted in Table 3. All the larvivorous fish species were collected from different types of freshwater aquatic habitats like pond, marshy wetlands, deep irrigation canals, shallow irrigation canals, rivulets and crop fields of Nalbari town area. The values of dissolved oxygen of each habitat are plotted in Table 4. Among all the larvivorous fishes Channa gachua was the dominant species collected from all types of aquatic habitats of Nalbari town. This species collected from habitats in which dissolved oxygen level ranged between 4.5± 0.18 mg/l and 8.6 ± 0.04 mg/l and regarded as a hardy and dissolved oxygen tolerant species. On the other hand species like Puntius sophore, P. ticto and Notopterus notopterus were collected higher from only those habitats with high dissolved oxygen content (6.8 ± ± 0.04 mg/l). Although the young ones of Channa gachua feed on mosquito larvae, the adults feed on small feeds on smaller fish and it is Figure 2: Dominance status of larvivorous fishes of urban areas of Nalbari Town (% per category) therefore, not suitable for anti-mosquito operations (Khanna, 1970). Predatory fishes like Channa, Notopterus and Mystus whose fry may destroy mosquito larvae but whose adults may predate upon other fish including larvicidal fish species. Gambusia affinis collected from only deep and shallow irrigation canals, while Aplocheilus panchax collected from ponds, marshy wetlands, shallow irrigation canals and crop fields. Both these two species are typical surface feeders, which fulfill the characteristic features of larvivorous fish (Hora and Mukherjee, 1938). Among the other fishes, species like Amblypharyngodon mola and Rasbora daniconius are sub-surface feeders. Column feeders like Puntius sp., Trichogaster sp., Chanda, Anabas, etc., which feed on mosquito larvae when chance permits. All the larvivorous fishes and their habitats are depicted in Table 5. REFERENCES APHA Standard methods for the examination of water and 381

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