Abstract:
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.
