The latency period of post-ovulation of Clariasgariepinus has been demonstrated to affect the viability of its eggs and embryos. This study has examined the effects of various latency periods on the viability of eggs, fertilization, hatchability and survival of the African catfish Clariasgariepinus. Progenies were produced using eggs successively stripped from the African catfish at 10, 12, 14, 16, 18, 20, 17, 14, 21 and 22 h of post-ovulation. Some eggs and sperm were delayed while others were used fresh. Low survival, hatchability and fertilization rates were observed in treatments 1 and 3 while an average percentage of fertilization, hatchability and survival rates were obtained in treatments 2 and 4. High rates of fertilization and hatchability as well as a considerable rate of survival of progeny after 21 days of indoor rearing was obtained in 14 h latency period at a temperature of 29.5°C and was significantly different (p<0.05). Therefore, any attempt to improve fingerlings production in Clariasgariepinus must consider the effects of latency period in relation to water temperature and the best latency period achieved in this study was 14
The effects of environment on the breeding nature of fish.
Fisheries have been recognized as one of the fastest growing sectors in the world. Fish is the most heavily traded food commodity in the market; with the continuous declining of natural fish production, it is crucial to improve fish production from aquaculture as it is one sector that can significantly contribute to World Fish Production (Gupta and Acosta, 2001). The production of marketable fish begins with the stocking of fry or juvenile into a rearing environment. These fish can come from wild capture, however the fish cannot be guaranteed that adequate numbers can be captured and stocked in the time corresponding to optimum production conditions; the fish farmer then naturally turns to other means of obtaining his stock which is invariably an artificial method (Oyelese, 2006). African catfish was one of the most suitable species in aquaculture it has been considered to hold a great promise for fish farming; the African catfish having a high growth rate, resistant to handling and stress, being very well appreciated and having a high market value. One key constraint to its culture is the limited availability of quality fingerlings as seed material (Sahoo et al., 2007). Induced breeding may be a dependable alternative for obtaining high quality seed material. The species of induced breeding of Clariasgariepinus depends largely on the Latency period (Hogendoorn and Vismans, 1980; Zonneveld et al., 1988). Latency period is being described as the time interval between injection of the female fish and stripping of eggs.
Fish breeding is a very important activity ensuring availability of fingerlings for the stocking of ponds and tanks etc. The breeding habits of fishes in nature differ from specie to specie, different species of fish choose different places in the aquatic environment for breeding. In Nigeria, induced breeding of African catfish through injection of ova prim (synthetic) hormone or pituitary gland is the main practice. Fish breeding is the act of producing young ones from parent brood fish. This ensures species continuity and survival. The ability to produce new living individuals is a characteristic feature of all living organism and is known as reproduction. Reproduction is the only means by which life is maintained.Fish breeding in hatcheries can be achieved by either natural methods or induced (artificial) breeding. In fishes, reproduction or breeding is controlled by some environmental factors. The environmental factors include temperature, Dissolved Oxygen salinity, good water quality, adequate food and photoperiod.