Gonad estimations. Every 14 days, the body weight of three fish of every treatment (one from each of the three replicates) was measured and recorded. Once the gonad began to develop and until spawning began, three females from each treatment were sac- rificed every 14 days to estimate the gonad weight. The ovaries were removed and weighed in an electrical monopan balance and the gonadosomatic index (GSI) was com- puted according to the formula of Dahlgren (1979): GSI (in %) = wet weight of gonad/wet weight of the fish x 100. Spawning. After attaining sexual maturity, two males and two females were randomly selected from each replicate and used for the spawning studies. One male B. splendens was paired with one female in a plastic trough containing fresh water at a depth of 15 cm. The female found shelter against the highly aggressive male on the water surface or under the plant tufts. The male built a foam nest, made of bubbles covered with saliva. Both partners were ready to spawn within 4-7 h. The females laid eggs within 24-30 h. Both the males and females collected the falling eggs and squeezed them into the nest. After completion of spawning, the female was removed from the trough to protect her from aggressive attacks by the male. The male dis- played a strong instinct to incubate the eggs. The number of eggs laid by the female was counted using a sterilized needle, without causing much disturbance. Fecundity is the number of eggs laid in a single spawn by an oviparous female (Mc Fadden et al., 1965). The male incubated the eggs intensively for 36 h, after which the fry hatched. The number of fry hatched and the number of unhatched eggs were counted. The hatching rate was calculated as: number of eggs hatched/num- ber of eggs laid x 100. The experiment lasted 77 days during which some pairs spawned three times. The remaining animals in the experimental tanks were removed and sacri- ficed for growth estimation. Statistical analysis. Students t test was applied to determine the significance of mean values between experimental groups. One- way ANOVA was applied to test the signifi-
Gonad estimations. Every 14 days, the body weight of three fish of every treatment (one from each of the three replicates) was measured and recorded. Once the gonad began to develop and until spawning began, three females from each treatment were sac- rificed every 14 days to estimate the gonad weight. The ovaries were removed and weighed in an electrical monopan balance and the gonadosomatic index (GSI) was com- puted according to the formula of Dahlgren (1979): GSI (in %) = wet weight of gonad/wet weight of the fish x 100. Spawning. After attaining sexual maturity, two males and two females were randomly selected from each replicate and used for the spawning studies. One male B. splendens was paired with one female in a plastic trough containing fresh water at a depth of 15 cm. The female found shelter against the highly aggressive male on the water surface or under the plant tufts. The male built a foam nest, made of bubbles covered with saliva. Both partners were ready to spawn within 4-7 h. The females laid eggs within 24-30 h. Both the males and females collected the falling eggs and squeezed them into the nest. After completion of spawning, the female was removed from the trough to protect her from aggressive attacks by the male. The male dis- played a strong instinct to incubate the eggs. The number of eggs laid by the female was counted using a sterilized needle, without causing much disturbance. Fecundity is the number of eggs laid in a single spawn by an oviparous female (Mc Fadden et al., 1965). The male incubated the eggs intensively for 36 h, after which the fry hatched. The number of fry hatched and the number of unhatched eggs were counted. The hatching rate was calculated as: number of eggs hatched/num- ber of eggs laid x 100. The experiment lasted 77 days during which some pairs spawned three times. The remaining animals in the experimental tanks were removed and sacri- ficed for growth estimation. Statistical analysis. Students t test was applied to determine the significance of mean values between experimental groups. One- way ANOVA was applied to test the signifi-
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