Effects of Photoperiod on Growth, Feed Conversion Efficiency, and Survival of Fry and Fingerlings of Mahseer, Tor putitora (Hamilton)

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1 The Israeli Journal of Aquaculture - Bamidgeh 6(4), 010, The IJA appears exclusively as a peerreviewed on-line Open Access journal at Sale of IJA papers is strictly forbidden. Effects of Photoperiod on Growth, Feed Conversion Efficiency, and Survival of Fry and Fingerlings of Mahseer, Tor putitora (Hamilton) Simple Sawhney* and Roopma Gandotra Department of Zoology, University of Jammu, Jammu (J&K) , India (Received , Accepted ) Key words: photoperiod, growth, feed conversion efficiency, Tor putitora Abstract The effect of photoperiod on the growth, feed conversion efficiency, and survival of mahseer (Tor putitora) fry and fingerlings was investigated in two simultaneous experiments. In the first experiment, triplicate groups of 0 fry (0.7±0.01 g) were stocked in 100-l plastic tubs. A flow-through system with aerators was used to maintain the optimum dissolved O level. The fish were exposed to one of four photoperiods (18 h light:6 h dark, 1 h light:1 h dark, 6 h light:18 h dark, and the natural photoperiod of 10 h light:14 h dark). The fry were fed a 45% protein diet at the satiation rate of 5% of body weight for 90 days in laboratory conditions. The best weight, specific growth rate, feed conversion efficiency, and survival were achieved in 18L:6D treatment. Fry performance was significantly retarded in the 6L:18D treatment. In the second experiment, triplicate groups of eight fingerlings (6.08±0.0 g) were stocked in 100-l tubs and exposed to the same photoperiods as in the first experiment. The fingerlings were fed a 8% protein diet at the rate of 5% body weight for 90 days. The growth performance of the fingerlings was not significantly affected by photoperiod. Results show that Tor putitora fry, but not fingerlings, reared in lab conditions are significantly affected by photoperiod regime. * Corresponding author. Mailing address: d/o Sh. Subash Chander Sawhney, H. no. 1, W. no. 9, Araya Samaj Gali, Udhampur (J&K), simplesimpu@ yahoo.co.in

2 Effect of photoperiod on growth of mahseer 67 Introduction Tor putitora Hamilton (Cypriniformes: Cyprinidae) is an important cyprinid fish, commonly known as mahseer and widely popular throughout the Indian subcontinent. Tor spp. once contributed a significant proportion of the natural stock of fish in Bangladesh, India, Nepal, and Pakistan (Chandra and Aminul Haque, 198). But, unfortunately, natural Tor stocks have been decimated to the extent that they are now considered a critically endangered species. Depletion of the mahseer population has been reported from all parts of India (Joshi, 1988; Nautiyal, 1994), Pakistan (Mirza and Khan, 1994), Nepal (Shrestha, 1994), Turkey (Balik, 1995), and Japan (Islam, 00). Many scientists have recommended that Tor fishes be given special attention so that they can be protected from extinction. One of the most important physical parameters for the growth and survival of fish larvae is photoperiod (Boeuf and Le Bail, 1999). Photoperiod is classified as a directive factor. It controls growth as a zeitgeber (cue or synchronizer) through its influence on endogenous rhythms and circulating levels of growth hormones (Simensen et al., 000). Many fish species react to photoperiod treatments. Extended and constant light increases the growth rate in juvenile mirror carp, Cyprinus carpio (Yagci and Yigit, 009). In some cases, the metabolic rate is not significantly affected by photoperiod (Imsland et al., 1995; Purchase et al., 000). In other cases, photoperiod affects larvae but not juveniles (Barlow et al., 1995). The present study was conducted to investigate the effects of photoperiod on growth, feed conversion efficiency, and survival of fry and fingerlings of Tor putitora. Materials and Methods Two experiments were conducted for 90 days (November -January 1): one on fry (0.7±0.01 g) and one on fingerlings (6.08±0.0 g). Fry were collected from the Anji Fish Farm, Reasi (J&K), and fingerlings from Jhajjar Kotli, a tributary of the Tawi river system. The experiments were conducted in laboratory conditions in a flow-through system consisting of 100-l plastic tubs and aerators. Water quality was monitored weekly. Dissolved oxygen was 6-7 mg/l, free Co was negligible, ph averaged 7.9 with negligible fluctuation, and water temperature was maintained at 6±1 C using thermostat-regulated heating rods. In the first experiment, triplicate groups of 0 fry per tub were stocked. The fry were exposed to one of four photoperiods: the control, i.e., natural photoperiod of 10 light:14 dark hours (10L:14D), and three treatments maintained in light proof chambers using day light tubes to create photoperiods of 6L:18D, 1L:1D, and 18L:6D. Automatic timers were used in the 1L:1D photoperiod; the 6L:18D and 18D:6L treatments were maintained manually. In the second experiment, triplicate groups of fingerlings were stocked at eight per tub and exposed to same photoperiods.

3 68 Sawhney and Gandotra Fry were fed a 45% protein diet and fingerlings a 8% protein diet (the optimum values were predetermined). The fish were fed each morning at a rate of 5% of their body weight. Uneaten feed was collected and weighed to estimate the feed conversion ratio, feed conversion efficiency, and other feed parameters. The fish were individually weighed every 15 days. Feed was withheld for one day prior to weighing and on the day of weighing. The percent weight, specific growth rate, food conversion ratio, food conversion efficiency, and protein efficiency ratio were determined according to Liu et al. (1998). One-way analysis (ANOVA) was conducted to test the effect of photoperiod on the growth of fry and fingerlings, using the computer program Analyse-it. Results There were significant differences (p<0.001) between photoperiods in the fry experiment (Table 1). Growth and feed conversion were significantly retarded by reducing the light phase to 6L:18D. Table 1. Effects of photoperiod on Tor putitora fry. Photoperiod Group Survival Control 10L:14D 1 6L:18D 1 1L:1D 1 18L:6D (g) Specific growth rate =(ln final wt ln initial wt)/no. days x 100 Feed conversion ratio = feed fed/wt Feed conversion efficiency = [(wt /feed fed)] x Protein efficiency ratio = increment in body wt/protein intake SGR FCR FCE PER 4 (%/d)

4 Effect of photoperiod on growth of mahseer 69 Weight and feed efficiency were not significantly affected by photoperiod in the fingerling experiment (Table ). Survival varied among treatments for both fry and fingerlings. Table. Effects of photoperiod on Tor putitora fingerlings. Photoperiod Group Survival Control 10L:14D 1 6L:18D 1 1L:1D 1 18L:6D (g) Specific growth rate =(ln final wt ln initial wt)/no. days x 100 Feed conversion ratio = feed fed/wt Feed conversion efficiency = [(wt /feed fed)] x Protein efficiency ratio = increment in body wt/protein intake SGR FCR FCE PER 4 (%/d) Discussion The response of Tor putitora to photoperiod regime depends on the developmental stage of the fish. Fry were more sensitive to photoperiod than fingerlings. Fry subjected to long periods of light (18, 1, or 10 h) had significantly better growth and feed conversion efficiency than those exposed to only 5 h light. Results were similar for gilthead sea bream (Tandler and Helps, 1985), tilapia (Rad et al., 006), mirror carp (Yagci and Yigit, 009), and rainbow trout (Sonmez et al., 009). Long periods of light improve performance of fish larvae probably because of increased food availability (Boeuf and Le Bail, 1999). Red light and continuous light promote survival and mass production of Wallago attu larvae compared to 1L:1D or 0L regimes (Giri et al., 00). A possible explanation for the retardation of growth and feed efficiency during shorter light periods may be the greater energy requirement of fry for synchronization of the endogenous rhythm of the fish to the external

5 70 Sawhney and Gandotra environment, leading to the reduction of somatic growth (Biswas and Takeuchi, 00). The improved growth performance of Tor putitora fry kept in longer periods of light might be due to the functioning of the pineal gland. The pineal gland is the major endogenous time-keeping system in teleosts and its secretion (melatonin) is reduced during periods of illumination (Hisar et al., 005). When the photoperiod rapidly increases, plasma growth hormones levels also increase (McCormick et al., 1995). In conclusion, photoperiod significantly affects growth of fry, but not of fingerlings in Tor putitora. A 18L:6D photoperiod is suggested for optimal growth during the fry stage while the natural photoperiod (10L:14D) could be used for fingerlings. References Balik S., Freshwater fish in Anatolia, Turkey. Biol. Conserv., 7(): 1-. Barlow C.G., Pearce M.G., Rodgers L.J. and P. Clayton, Effect of photoperiod on growth, survival, and feeding periodicity of larval and juvenile barramundi Lates calcarifer (Bloch) Aquaculture, 18: Biswas A.K., Endo M. and T. Takeuchi, 00. Effect of different photoperiod cycles on metabolic rate and energy loss of both fed and unfed young tilapia Oreochromis niloticus: Part I. Fish. Sci., 68: Boeuf G. and P.Y. Le Bail, Does light have an influence on fish growth? Aquaculture, 177: Chandra K.J. and A.K.M. Aminul Haque, 198. Studies on the biology of Tor spp. in natural and artificial waters of Bangladesh: II - taxonomy. Bangladesh J. Fish., -5(1-): Giri S.S., Sahoo S.K., Sahu B.B., Sahu A.K., Mohanty S.N., Mukhopadhyay P.K. and S. Ayyappan, 00. Larval survival and growth in Wallago attu (Block and Schneider): effects of light, photoperiod and feeding regimes. Aquaculture, 1: Hisar S.A., Kirim B., Bektas S., Altinkaynak K., Hisar O. and T. Yanik, 005. Effect of photoperiod on plasma thyroxine hormone level of mirror carp (Cyprinus carpio) raised at a low water temperature in a controlled environment. Isr. J. Aquacult. - Bamidgeh, 57(1):19-4. Imsland A.K., Folkvord A. and S.O. Steffanson, Growth, oxygen consumption and activity of juvenile turbot (Scophthalmus maximus L.) reared under different temperatures and photoperiods. Neth. J. Sea Res., 4: Islam M.S., 00. Evaluation of supplementary feeds for semi-intensive pond culture of mahseer, Tor putitora (Hamilton). Aquaculture, 1:6-76. Joshi CB., Mahseer fishery of some hill streams in western Himalayas. Indian J. Fish., 5(4):9-7. Liu F.G., Yang S.D and H.C. Chen, Effect of temperature on feed response, growth performance, and muscle proximate composition in juvenile hybrid striped bass (Morone saxatilis x M. chrysops). Isr. J. Aquacult. - Bamidgeh, 50:

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