The sexual maturity of female sultan fish, Leptobarbus hoevenii was studied by determining fecundity and gonadosomatic index (GSI). It was found that the size at sexual maturity of female sultan fish was with 40.85±3.80 cm in total length and 783.00±217.46 g in body weight. Fecundity was 76,414.69±36,586.61 ova/fish and gonadosomatic index (GSI) was 8.14±3.92%.
The artificial breeding injection was carried out by using synthetic chemical (Suprefact 20 µg/kg and Motilium 5 mg/kg) for induced spawning, male and female brooders were done by once injection. The trials about hatching rate and hatching period were carried out in a 15-liter glass aquarium (water volume 12 liters), containing 1,000 eggs and there replications in each trial. It was found that the average of hatching rate was 82.6% and hatching out was 22 hours 44 minutes at 27-29 °C of water temperature.
The newly hatched larvae were 4.05±0.24 mm in total length with yolk sac of 77.625 mm3 in volume. The yolk sacs were completely absorbed within 108 hr after hatching. All the larvae opened their mouth at about 36 hr after hatching (4.42±0.20 mm TL) with mouth measuring 182.36 mm in height.
Feeding experiments were carried out in the 15-liter glass aquarium with 10 liters of water containing 600 larvae aged 2.5 days post-hatching and feed them by Moina. At 2-hourly intervals, 20 larvae were collected randomly from the aquarium, At 62 hr after hatching, the mouth size was measured to be 412.27 mm. The onset of feeding showed 0.05 individual Moina/ larvae.
A starvation of newly hatched larvae was studied in the 15-liter aquarium with 12 liters of water by three replications. In each replication contained 300 newly hatched larvae by without feeding, observed every 2 hours. This trial was found that totally larvae died within 112 hours after hatching at water temperature ranging between 27.0 and 29.5 °C.
KEWWORDS: Breeding technique, Larvae, Hatching, Starvation, Sultan fish,
Leptobarbus hoevenii (Bleeker, 1851)