Abstract:
The study of environmental factors including temperature, photoperiod and pH from the dried Terminalia catappa extract to either sex ratio and growth performance of halfmoon fancy betta fish. The objective is to reduce breeding problems for halfmoon betta fish in the cool season (October - February) which the number of male fry and the survival rate of halfmoon betta fish fry is decrease. There were 4 experiments the first experiment was the study on the different water temperatures affecting on sex ratio in larvae. The results showed that soaked fertilized eggs at different water temperatures at 28-29 (control), 24-25, 30-31, 32-33 and 34-35°C, the survival rate of larvae was significantly different (P<0.05). The temperature at 28-29°C gave the highest survival rate of larvae at 83.67 ± 17.43%. The sex ratio of larvae was not significantly different (P>0.05) The nursery of larvae after 7 and 14 days post hatch underwater at temperature (control), 30 and 32°C revealed that the survival rate and sex ratio were not significantly different (P>0.05). The second experiment was study on photoperiod that affecting to breeding and sex ratio in Betta splendens. The results showed that the photoperiod of different ratio as: 0L: 24D (control), 24L: 0D, 8L: 16D, 12L: 12D and 16L: 8D gave in the number of eggs, egg weight, fecundity in breeder and the hatching rate with a significant difference (P<0.05) when 0L: 24D presented the highest number of eggs and fecundity with an average of 1,002.5±1.98 eggs and 1,106.62±2.72 eggs / fish, respectively and photoperiod at 24L: 0D, average egg weight and hatching rates average were 1.24±0.01g and 62.18± 14.21% and there were no significantly different with the 0L: 24D (P>0.05). The sex ratio and survival rate of larvae were not significant difference (P>0.05). The different photoperiods showed the effect on the development of gamete in the breeder. The female B. splendens, the stage of egg cell development can be found in stage 2-6 and the male B. splendens development of germ cells was in primary spermatocytes, secondary spermatocytes, spermatids and spermatozoa. The third experiment, study the effect of pH from the different quantities of dried Terminalia catappa leaf extract on sex ratio, survival rate and growth performance of halfmoon betta fish. It was found that the amount of tannin in the dried T. catappa leaves at 0, 2.5, 5, 7.5 and 10 g were significantly different (P<0.05). The 10 g of dried T. catappa leaves contains the maximum tannin 943±0.01 ppm. Soaking the different quantity of dried T. catappa leaves in a water period of 24 hours to change pH in the water. There was a significant difference (P <0.05) at 15 hours. The pH from T. catappa leaves soaked water at 0, 2.5, 5, 7.5 and 10 g/l. As a results, spawning rate and survival rate of breeder and survival rate of larvae were significantly different (P<0.05). The pH from dried T. catappa leaves water soaked 2.5 g/l (pH 6.67) presented the highest spawning rate at 80.0±44.72 % but the pH from dried T. catappa leaves 10 mg/l (pH 5.91) caused all breeders and larvae to die. Immersion of fertilized eggs in pH water from different amounts of T. catappa leaves affected to male ratio and growth performance of the B. splendens larvae. It was found that the amount of dried T. catappa leaves at 5 g/l (pH 6.71) resulted in the highest male larvae 74.13±9.08 % and increased the number of male larvae 35.27±22.97% differ from control (pH 7.50). The growth of fighting fish larvae were not significantly different (P>0.05). The fourth was the experiment comparison of culture and control factors (environmental sex determination; ESD) on sex ratios in halfmoon betta fish. It was found that breeding and nursing of halfmoon betta fish with controlled factors during November 2019 January 2020 (Cool season) and December 2019 February 2020 (Late cool seasoon), resulting in survival rates and sex ratios were significantly different (P<0.05). Therefore, the breeding process of halfmoon betta fish by controlling environmental factors beging with breeding of breeder in the photoperiod at 24L: 0D, followed by the immersion of dried T. catappa leaves at 5 g /l for 15 hours in fertilized eggs and nursed the larvae 7 days at 30 °C for 14 days. It might be promising to breed halfmoon betta fish in the winter and increase the number of male larvae 25-35%.