Songklanakarin Journal of Science and Technology (SJST) (Oct 2014)
Some aspects in early life stage of giant gourami, Osphronemus goramy (Lacepede) larvae
Abstract
The sexual maturity of female giant gourami, Osphronemus goramy was studied by determining fecundity and gonadosomatic index (GSI). It was found that the size at sexual maturity of female giant gourami was with 33.88±7.42 cm in total length (mean ± SD) and 968.75± 68.78 g in body weight. Fecundity was 5,508±1,547 ova/fish and gonadosomatic index (GSI) was 2.32±0.5%. Newly hatched larvae of giant gourami were produced by semi-controlled natural method. The hatching period, hatching out and hatching rate experiments were carried out in a 15-liter glass aquarium (water volume 10 liters) containing 300 eggs. It was found that the eggs were floating and rounded. The fertilized eggs had a diameter of 2.185±0.19 mm. The average hatching out was 26 hr 18 min, hatching period was 6 hr 13 min and hatching rate was 61.60% at water temperature of 28-30° C. The newly hatched larvae were 4.48±1.41 mm in total length with yolk sac volume of 7.768.72±1.205.83 mm3 . The yolk sacs were completely absorbed within 228 hr after hatching. All the larvae opened their mouth at about 50 hr after hatching (6.87±0.10 mm TL) with mouth measuring 324.30144.60 mm in height. Feeding experiments were carried out in 15-liter glass aquaria with 10 liters of water containing 1000 larvae aged 1.5 days post-hatching (before mouth opening. Moina was fed to them at a density of 10 individual/ml. At 2-hourly intervals 20 larvae were collected randomly from the aquarium, preserved in 10% formalin and then dissected to determine Moina in the digestive tract. At 110 hr after hatching, the mouth size was measured to be 486.45±14.47 mm. The onset of feeding showed 0.27 individual Moina/ larva.
