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A study on the effect of water salinity ranging from 0-30 ppt on hatching success of snake head fish, Channa striatus was conducted in a 15-liter glass aquarium (water volume 10 liters) containing 500 eggs for various levels of water salinity. Fertilization rates at 0, 5, 10, 11, 12, 13 and 14 ppt were 69.33, 72.67, 71.33, 72.67, 82.00, 73.33 and 10.67%, respectively. The fertilization rate at 12-13 ppt salinity was significantly (P0.05) among 0, 5 and 10 ppt.

A study on the effect of water salinity ranging from 0-30 ppt on hatching success of snake head fish, Channa striatus was conducted in a 15-liter glass aquarium (water volume 10 liters) containing 500 eggs for various levels of water salinity. Fertilization rates at 0, 5, 10, 11, 12, 13 and 14 ppt were 69.33, 72.67, 71.33, 72.67, 82.00, 73.33 and 10.67%, respectively. The fertilization rate at 12-13 ppt salinity was significantly (P<0.05) higher than that at 0, 5, 10 and 11 ppt salinity. Hatching rate at 0, 5, 10, 11, 12, 13 and 14 ppt salinity were 60.00, 60.67, 66.67, 72.00, 77.33, 68.00 and 2.67%, respectively. Hatching rate at 12 ppt salinity was significantly (P<0.05) higher than that at 0, 5, 10, 11 and 13 ppt salinity. For the snake head fish, the water salinity of 12 ppt was shown to give the highest fertilization and hatching rates. The times of hatching out at water salinity of 0-14 ppt were between 1,192-1,442 minutes. After hatching, the survival tolerance of snake head fish larvae in different salinity (0-30 ppt) within 24 hour were then studied using a 50-liter glass aquarium (water volume 30 liters) containing 50 larvae at each level of salinity. All treatments were done in triplicate. The survival rate of fish larvae in the 0, 5, 10, 15, 16, 17, 18, 19, 20, 25 and 30 ppt salinity were 100, 100, 100, 100, 0, 0, 0, 0, 0, 0 and 0 %, respectively. However, fish larvae that had survived at 15 ppt died after 8 days of rearing. The gain rate of total body length, body weight gain rate and survival rate (%) at 10 weeks at water salinity ranging from 0, 5 and 10 ppt were significantly (P<0.05) higher than that at 11, 12, 13 and 14 ppt salinity. However, there were no significance differences (P>0.05) among 0, 5 and 10 ppt. [ABSTRACT FROM AUTHOR]

The sexual maturity of female snake head fish, Channa striatus was studied by determining fecundity and gonadosomaticindex (GSI). It was found that the size at sexual maturity of female snake head fish was 26.45±3.07 cm (mean ± SD,n=10) in total length and 167.4±48.09 g in body weight. The eggs were floating and rounded. The fertilized eggs had a diameterof 588±20.43 m. The fecundity was 10,279.1±2,527.9 ova/fish and gonadosomatic index (GSI) was 5.07±1.04 %.Newly hatched larvae of snake head fish were produced by induced spawning using chemical injection (Suprefactand Motilium). The sexually mature fishes were cultured in a fiber-glass tank (water volume 300 liters) with the ratio of maleand female brooders 1:1. The fertilization rate, hatching out and hatching rate experiments were carried out using 3 15-literglass aquaria (water volume 10 liters) each containing 1,000 eggs. It was found that the average fertilization rate was 76.50%,hatching out occurred of 28 hr 40 min and average hatching rate was 60.26 % at a water temperature of 26.5-29.0°C. Samplingof the newly-hatched larvae was done at 2-hour intervals, when 20 of them were randomly taken and preserved in 10%buffered formalin for later determination of yolk absorption time. Observation using a microscope revealed that newlyhatched larvae were 3.18±0.11 mm in total length and had yolk sacs of 1,279.71±196.10 m3 in volume. The yolk sacs werecompletely absorbed within 80 hr after hatching at a water temperature of 26.5-29.0°C. Up until full mouth development (startof feeding), 2-hourly samplings of twenty newly hatched larvae were taken from an aquarium for observation of the size ofmouth opening. All the larvae had open mouths about 52 hr after hatching (5.48±0.16 mm TL), and measured 324.30±144.60m in mouth opening.The feeding experiments were carried out using a 15-liter glass aquarium (water volume 10 liters) containing 1,000larvae aged 1.5 days post-hatching (just before the mouth opened). They were fed with Moina at a density of 10 individual/ml. Twenty larvae were collected at random from the aquarium at 2-hourly intervals, preserved in 10 % buffered formalin, andthen dissected to determine the presence of Moina in the digestive tract. The digestive tracts were fixed at 62 hr of hatchingat water temperatures of 28.0-30.5°C, and measured 334.87±149.78 m in mouth opening. The average number of Moina inthe digestive tract at the start of feeding was 0.56 individual/larva.

Feeding scheme experiments were done in a 15-liter glass aquarium (water volume 10 liters) containing 500 of two-dayold larvae (stage at first feeding). It was found that larval snake head fish aged 3-11 days (average total length 6.08-10.86 mm)consumed Moina. Larvae aged 12-15 days (average total length 10.79-14.61 mm) consumed both Moina and commercialpellet (40 % crude protein). Larvae aged more than 16 days consumed only commercial pellet.Determining the daily food uptake by the larvae and juveniles was done in a 15-liter glass aquarium (water volume 10liters) containing 1,000 larvae. The larvae consumed Moina ,provide of a density of Moina 10 individual/ml. The amount offood intake was calculated based on changes of food density in the aquarium with and without fish larvae at 2-hour intervals.It was found that larvae aged 3-15 days consumed Moina. The average uptake of Moina in digestive tract per day of larvaeage 3, 6, 9, 12 and 15 days old was 28.7, 115.70, 162.27, 195.30 and 227.30 individual/larva, respectively at water temperaturesranging between 25 and 28°C.A starvation experiment was carried out using a 15-liter glass aquarium (water volume 10 liters) with three replications.Two hundred newly hatched larvae were kept without feeding. Larvae started to die at 216 hr and totally died within 326 hrafter hatching at water temperature ranging between 28.0 and 30.5°C.

Feeding scheme experiments were done in a 15-liter glass aquarium (water volume 10 liters) containing 500 of two-day old larvae (stage at first feeding). It was found that larval snake head fish aged 3-11 days (average total length 6.08-10.86 mm) consumed Moina. Larvae aged 12-15 days (average total length 10.79-14.61 mm) consumed both Moina and commercial pellet (40 % crude protein). Larvae aged more than 16 days consumed only commercial pellet. Determining the daily food uptake by the larvae and juveniles was done in a 15-liter glass aquarium (water volume 10 liters) containing 1,000 larvae. The larvae consumed Moina ,provide of a density of Moina 10 individual/ml. The amount of food intake was calculated based on changes of food density in the aquarium with and without fish larvae at 2-hour intervals. It was found that larvae aged 3-15 days consumed Moina. The average uptake of Moina in digestive tract per day of larvae age 3, 6, 9, 12 and 15 days old was 28.7, 115.70, 162.27, 195.30 and 227.30 individual/larva, respectively at water temperatures ranging between 25 and 28°C. A starvation experiment was carried out using a 15-liter glass aquarium (water volume 10 liters) with three replications. Two hundred newly hatched larvae were kept without feeding. Larvae started to die at 216 hr and totally died within 326 hr after hatching at water temperature ranging between 28.0 and 30.5°C. [ABSTRACT FROM AUTHOR]

The sexual maturity of female snake head fish, Channa striatus was studied by determining fecundity and gonadosomatic index (GSI). It was found that the size at sexual maturity of female snake head fish was 26.45±3.07 cm (mean ± SD, n=10) in total length and 167.4±48.09 g in body weight. The eggs were floating and rounded. The fertilized eggs had a diameter of 588±20.43 µm. The fecundity was 10,279.1±2,527.9 ova/fish and gonadosomatic index (GSI) was 5.07±1.04 %. Newly hatched larvae of snake head fish were produced by induced spawning using chemical injection (Suprefact and Motilium). The sexually mature fishes were cultured in a fiber-glass tank (water volume 300 liters) with the ratio of male and female brooders 1:1. The fertilization rate, hatching out and hatching rate experiments were carried out using 3 15-liter glass aquaria (water volume 10 liters) each containing 1,000 eggs. It was found that the average fertilization rate was 76.50%, hatching out occurred of 28 hr 40 min and average hatching rate was 60.26 % at a water temperature of 26.5-29.0°C. Sampling of the newly-hatched larvae was done at 2-hour intervals, when 20 of them were randomly taken and preserved in 10% buffered formalin for later determination of yolk absorption time. Observation using a microscope revealed that newly hatched larvae were 3.18±0.11 mm in total length and had yolk sacs of 1,279.71±196.10 µm³ in volume. The yolk sacs were completely absorbed within 80 hr after hatching at a water temperature of 26.5-29.0°C. Up until full mouth development (start of feeding), 2-hourly samplings of twenty newly hatched larvae were taken from an aquarium for observation of the size of mouth opening. All the larvae had open mouths about 52 hr after hatching (5.48±0.16 mm TL), and measured 324.30±144.60 µm in mouth opening. The feeding experiments were carried out using a 15-liter glass aquarium (water volume 10 liters) containing 1,000 larvae aged 1.5 days post-hatching (just before the mouth opened). They were fed with Moina at a density of 10 individual/ml. Twenty larvae were collected at random from the aquarium at 2-hourly intervals, preserved in 10 % buffered formalin, and then dissected to determine the presence of Moina in the digestive tract. The digestive tracts were fixed at 62 hr of hatching at water temperatures of 28.0-30.5°C, and measured 334.87±149.78 µm in mouth opening. The average number of Moina in the digestive tract at the start of feeding was 0.56 individual/larva. [ABSTRACT FROM AUTHOR]