Photoperiodic regulation is not exclusively limited to the control of reproductive rhythms, but may also affect other physiological processes. The effect of photoperiod on the growth and development of freshwater ornamental fish (Pocellia sphenops) shows that the length and weight of the 24-hour photoperiod are more important than the 12-hour photoperiod (Jeniffer et al., 2012). ). First, manipulation of the light period can accelerate, maintain, or delay sexual maturation and spawning of the breeding flock so that spawning can occur out of season.
Second, manipulation of the photoperiod can also inhibit gonadal regrowth so that somatic growth can be encouraged in growing fish without the energy drain required for reproduction (Lamet al., 1983). In the female, there is a large percentage of the available energy that goes into reproduction (Whittier and Crews, 1987). One of the most important factors controlling chromatophore output by pigment aggregation or dispersion is the intensity of light.
The pigments in ornamental fish are one of the most important quality variables that dictate market value. Five percent of the total biomass in each tank was fed commercial food (aquarium fish powder) with a diet (moisture 12%, crude protein 26%, crude fat 5%, carbohydrate 35% and fiber 7%). Length increase (cm) = Final length of the fish body – Starting length of the fish body.
Immediately after the end of the experiment, the total carotenoid concentration (TCC) in the muscle tissue of the fish was analyzed.
Some Pictures
CHAPTER FOUR RESULTS
- Effects of photoperiod on fish weight
- Effects of photoperiod on length gain
- Effects of photoperiod on survival rate
- Effect of photoperiod on reproduction rate of platy
Fish body weight gain was calculated every fortnight by subtracting the current sampling weight from the fish weight at the immediately previous sampling and is shown in Figure 3 and in Appendix 5. Fish length increase was calculated every fortnight by subtracting the current fish length at sampling from length of fish in the immediate previous sampling and shown in Figure 4 and in Appendix 6. The greatest increase in length was in the T2 treatment during the 1st sampling and the smallest during the 3rd sampling.
Effects of photoperiod on survival and mortality rate of flatfish are recorded in Table 3 and Appendix-11. Mean weight, mean length and mean fish SGR of T2, T3 and T4 fish were compared with the control group (T1). T1 and T2 were statistically significantly different from the other treatments, and there was no difference between T3 and T4.
22 Figure-8: Effects of photoperiod on mean SGR of fish (mean ± SD) were shown after 5 months. Table 4 and Appendix 12 showed that, among the four treatments, spawning fish treated with T2 (0 hr D: . 24 hr L) gave birth early. The carotenoid content of fish under different photoperiodic levels was calculated after the completion of this experiment and shown in Figure 9 and Appendix 9.
In carotenoid content analysis after T2 treatment, fish from T1 treatment gave a large amount of carotenoid from others. Figure-10: Effects of the photoperiod on mean carotenoid content of fish (mean ± SD) content was shown after 5 months. T2 was statistically significantly different from other three treatments and there was no difference not only T3 and T4 but also T1 and T3.
CHAPTER FIVE DISCUSSION
- Effects of photoperiod on fish Weight
- Effects of Photoperiod on Fish Length
- Effects of Photoperiod on Fish Growth Performance
- Effects of Photoperiod on Survival Rate of Platy
- Effects of Photoperiod on Fish Reproduction
- Effects of Photoperiod on Coloration and Carotenoid Content of Platy fish
In the present study period, photoperiod improved plaque growth performance and the highest final weight was found in T2 treatment. T2 (0 h D: 24 h L) treated fish had higher weight, weight gain, length and growth than other fish. Fish with a long day photoperiod had better growth performance than other fish because they helped secrete growth hormone by affecting the pituitary gland (Baggerman, 1980). There is no significant difference in survival rate between different photoperiod levels, suggesting that the longer photoperiod does not cause any lethal effect.
2003) indicated that black bass mortality during the experimental period did not show significant differences between treatments nor was it related to photoperiod. Although the most common cause of death was due to male-female fights during mating (Howell et al., 2003). This present experiment was conducted to determine the effect of photoperiod length on larval duration, growth to metamorphosis, and the early juvenile phase.
Light is one of the most important culture management factors in that it synchronizes from embryo development to sexual maturation of fish (Guo et al., 2012; Villamizar et al., 2011). In T2 treatment, Platy's breeding rate was the highest and it took less time than other treatments to breed. It was shown in this research that the T2-treated platy took the shortest time, which was 113 days (average) among four treatments.
Photoperiod directly affects fish behavior, particularly their feeding and reproductive habits (McConnell, 1999). The results of this color observation study suggested that fish raised under higher light level conditions (in the T2 treatment) showed brighter colors than other photoperiod levels. Color changes in fish are often related to environmental stress, and light may be a major factor regulating pigment distribution through hormone regulation (Salm et al., 2004).
The color of fish skin depends mainly on the presence of chromatophores containing colored pigments (Fox, 1957). Fish skin color is created by the absorption, reflection, and scattering of light by pigments and microstructures within the fish's integument (Fujii, 2000). Therefore, the result obtained from the present study shows that the highest light level (T2) was more suitable to improve the skin color of the slant fish, which could be recommended for the successive development of this high-priced species. .
CHAPTER SIX CONCLUSION
CHAPTER SEVEN
RECOMMENDATION AND FUTURE PROSPECTS
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