http://repository.rjt.ac.lk/handle/123456789/7714 2026-04-11T22:01:36Z http://repository.rjt.ac.lk/handle/123456789/7716 INDUCED BREEDING AND EVALUATION OF SUITABLE FEED FOR LARVAL REARING OF THE ENDEMIC FISH Mystus nanus (SUDASINGHE, PETHIYAGODA, MADUWAGE & MEEGASKUMBURA, 2016) Darshanie, P.S.N.; Sundarabarathy, T.V.; Mudalige, A.R. The striped dwarf catfish, Mystus nanus, recently recognized as an endemic species of Sri Lanka, is the focus of a study aimed at enhancing its conservation through captive breeding programs. This research evaluates the most effective hormone for inducing breeding and the optimal feed for larval rearing. A total of 27 males and 13 females were collected from the Kala Oya spill, North Central Province of Sri Lanka. They were fed with commercial feed for tropical fish (protein content 42%) ad libitum. After a month of acclimatization, the broodstock were used for induced breeding trials with a male-to-female sex ratio of 2:1. Three hormone treatments were tested, each with three replicates: Ovulin (sGnRH analogue + domperidone), LHRHa + domperidone, and HCG, with natural breeding serving as the control. Ten-day-old postlarvae were randomly assigned to four different dietary treatments with at a stocking density of 2 postlarvae/L (50 postlarvae /tank); soya yogurt, Artemia nauplii, microworms, and commercial feed (control), with three replicates for each treatment. All three replicates of the Ovulin treatment successfully induced spawning, while only one replicate each of the LHRHa + domperidone and HCG treatments led to successful spawning. Natural spawning did not occur during the one-month period. No significant differences (P > 0.05) were observed among the hormone treatments in terms of total eggs spawned, relative fecundity, fertilization rate, hatchability, and survival rate. The latency period varied across treatments: Ovulin (8–10 hours), LHRHa + domperidone (9–11 hours), and HCG (6–8 hours). Fry fed soya yogurt showed the best growth performance, with final length of 24.70 ± 0.17 mm, final weight of 178.50 ± 2.31 mg, weight gain of 173.96 ± 2.58 mg, length gain of 17.50 ± 0.19 mm, SGR-W of 12.46 ± 0.27 % per day, SGR-L of 4.11 ± 0.03 % per day, and survival rate of 78.33 ± 0.88 %. In contrast, the lowest growth and survival were recorded in fry fed with microworms (P < 0.05), with final weight of 50.36 ± 1.43 mg, final length of 15.13 ± 0.02 mm, weight gain of 45.90 ± 1.36 mg, length gain of 7.97 ± 0.25 mm, SGR-W of 8.04 ± 0.08 % per day, SGR-L of 2.49 ± 0.05 % per day, and survival rate of 25.67 ± 1.20 %. The length–weight relationship analysis indicated that fish fed with soya yoghurt exhibited isometric growth (b = 3). It is recommended that the use of Ovulin hormone at a dosage of 0.5 mL/kg body weight in females is more effective for inducing breeding. Furthermore, soya yogurt has been identified as the most effective feed for larval rearing under captive breeding conditions. These practices are expected to be adopted for the conservation of M. nanus. 2025-06-04T00:00:00Z http://repository.rjt.ac.lk/handle/123456789/7715 AQUACULTURE POTENTIAL OF Labeo heladiva: BREEDING, EMBRYOGENESIS AND LARVAL MANAGEMENT Bandara, R.B.M.G.N.; Sundarabarathy, T.V.; Mudalige, A.R. Labeo heladiva (Teleostei: Cyprinidae) is slow-growing, endemic minor cyprinid species in Sri Lanka with potential as a sustainable nutrient option to combat malnutrition within the country. This study aimed to investigate its feasibility of induced breeding, document the stages of embryonic development, and assess the growth and survival of postlarvae reared under different captive conditions as there is no existing literature regarding these aspects. Broodstock of L. heladiva were collected from Janaranjana Wewa, Kantale, Eastern province of Sri Lanka. Induced breeding was conducted using synthetic hormone, Ovulin® (sGnRHa + Dompeidone). Female brooders were administrated three hormone doses viz., 0.5, 0.4, 0.3 mL/kg while male received 0.25 mL/kg. A 1:1 male to female ratio was used for the breeding trials, each conducted in triplicate. Embryonic and larval development stages were observed and recorded up to 75 hours of post-egg release at average water temperature of 26.5˚C. Postlarvae were reared under three different conditions at a stocking density of 12 larvae/10L: jars (E1), hapa in a mud pond (E2), and a combined method where larvae were first reared in jars for one week and then transferred to hapa for two weeks (E3). Each treatment was replicated three times and conducted for period of three weeks. All hormone dosages resulted in successful spawning within a latency period of 9–10 hours. The highest average egg count (120,825 ± 2875.20) was recorded with the 0.5 mL/kg dosage, while the lowest (59,070 ± 1753.80) was observed with the 0.3 mL/kg dosage. The eggs of L. heladiva hatched at 28 hours, while the embryogenesis is completed by 25 hours. The hatchlings fully absorbed the yolk sac by 75 hours. A negative allometric growth pattern was observed among postlarvae in all experiments. The highest mean weight gain, relative growth rate (RGR-W), and specific growth rate (SGR-W) were observed in the hapa-reared larvae (E2), whereas the lowest was found in jar-reared larvae (E1) (P < 0.05). However, the growth parameters for larvae from combined method (E3) were not significantly different from either E1 or E2 (P > 0.05). The highest survival rate was recorded in jar (E1) and combined method (E3), which were significantly differ (P < 0.05) from those in hapa (E2). In conclusion, the successful captive breeding of L. heladiva can be achieved with 0.5, 0.4, 0.3 mL/kg doses using Ovulin®. The use of 0.5 mL/kg Ovulin® for breeding, together with the combined (E3) larval rearing method, ensures optimal growth and survival in L. heladiva, supporting its viability for aquaculture expansion. 2025-06-04T00:00:00Z