~ 398 ~ Journal of Entomology and Zoology Studies 2020; 8(2): 398-403 E-ISSN: 2320-7078 P-ISSN: 2349-6800 www.entomoljournal.com JEZS 2020; 8(2): 398-403 © 2020 JEZS Received: 04-01-2020 Accepted: 06-02-2020 R Siju Ph.D. Scholar, Division of Aquaculture, ICAR-Central Institute of Fisheries Education (CIFE), Panchmarg, Andheri West, Mumbai, Maharashtra, India VK Tiwari Principal Scientist, Division of Aquaculture, room no: 004, ICAR-Central Institute of Fisheries Education (CIFE), Panchmarg, Andheri West, Mumbai, Maharashtra, India Sunil Kumar Nayak Powerkheda Sub-centre, ICAR- Central Institute of Fisheries Education (CIFE), Madhya Pradesh, India Babitha Rani Senior Scientist, Division of Aquaculture, room no: 004, ICAR-Central Institute of Fisheries Education (CIFE), Panchmarg, Andheri West, Mumbai, Maharashtra, India Corresponding Author: VK Tiwari Principal Scientist, Division of Aquaculture, ICAR-Central Institute of Fisheries Education (CIFE), Panchmarg, Andheri West, Mumbai, Maharashtra, India Optimization of photoperiodism on growth and survival of Clarias batrachus (Linnaeus, 1758) larvae R Siju, VK Tiwari, Sunil Kumar Nayak and Babitha Rani Abstract Effect of photoperiod on growth and survival of Clarias batrachus (Linnaeus, 1758) larvae were studied under Five different photoperiodic conditions: 24L (hrs. light):0D (hrs. dark) (T1), 18L: 6D (T2), 6L: 18D (T3), 0L: 24D (T4)), 12L: 12D (C). Average body weight (542.60±11.89 mg), specific growth rate (SGR) (7.43±0.04) and percentage weight gain (PWG) (4010.6±50.10) obtained in T3 (6L: 18D) photoperiodic condition was found to be significantly (p<0.05) higher than other treatments. The allometric coefficient “b” obtained is higher for T3 (6L: 18D) and T4 (0L: 24D) which indicates more larval growth potential. The polynomial 2-parameter model indicated the best fit to explain and predict body weight and length of larvae with the increase in age. Higher growth and survival is recorded in 6L:18D which can be attributed to better feed intake, higher melatonin synthesis and suppression of swimming activity and stress in dark condition. The photoperiod (6L: 18D) may be recommended as a simple, low-cost technique to maximize the hatchery production of C. batrachus larvae. Keywords: Clarias batrachus, larvae, photoperiod, growth, survival 1. Introduction The Asian catfish, Clarias batrachus (Linnaeus, 1758) in India, popularly known as Magur is an economically important air-breathing catfish. It has good market demand, especially in North-Eastern parts, like in the states of Assam, Meghalaya, Tripura, and also in Andhra Pradesh, Uttar Pradesh, Karnataka, Maharashtra, Tamil Nadu, Bihar, Orissa and West Bengal which support significant natural fishery of this species [1] . The fish is revered as nutritious and therapeutic. C. batrachus is naturally distributed in two major riverine systems of India viz., Ganga and Brahmaputra and is also found in other freshwater bodies like bheels, wetlands and swamps in Northern and North-Eastern India and global distribution beyond India is in Nepal, Bhutan, and Bangladesh [2] . Magur is found in all types of waters but more so is in derelict and swampy waters. It can live out of water for quite some time and move short distances overland with the help of functional accessory respiratory organ [3, 4] It attains maturity within the first year of life and spawns typically from April to August, during onset of monsoon time in both open and confined waters [5, 6, 7] . However, the culture practice of this species has not received much importance throughout the country, probably due to inadequate supply of seed and due to lack of proper feeding management. Brood stock management, induced spawning using pituitary extracts, Ovaprim or Ovatide, stripping, incubation and hatching of fertilized eggs were demonstrated in the flow-through hatchery system by different workers [1, 8, 9] . Larval phase of this fish is considered as the most delicate and sensitive stage for handling and rearing in its life history. Even though the seed rearing technology is standardized to many extends the growth rate and survival rate of larvae at farm level is relatively low. More care should be given for the larval stocking and its diets (either live feeds or formulated diets). C. batrachus are bottom feeders, so these seem to suggest that restriction of light may be used in its culture to for reducing stress and better feeding, which enhance the growth and survival. Photoperiod exposure is one of the most promising physical factor governing increase in growth rate and survival of fish larvae and photoperiod manipulation is one of the low-cost and straightforward techniques to obtain reasonable growth rate and survivability of fish larvae [10] . Studies on photoperiod also report the influence on body colouration and gonadal development activity for different fishes [11] . The constant change between day and night affect the physiology, feeding efficiency, and metabolism of the fish.