1.0 Introduction
The hatchability of Dutch Clarias gariepinus. The successful large-scale cultivation of any organism for human consumption demands that the resources be easily renewable (Harvey and Hoar, 1979) it is clearly of no use of cultivate any organism when the supply of the young cannot be easily replenished. Among the numerous species of fish under cultivation in Nigeria notabily are common carp, cat fish (Clarias gariepinus)heterobranchus spand Tilapia sp.
The culture potential of Clarias gariepinus and Heterobranchus have been discussed by a number of authors among are Micha (1973) Legendre (1986) etc. The steadily growing importance of fishery product has compelled, improvements in the technologies necessary to boosting its production. Aquaculture production of Clarias gariepinus has been practiced for a long time in Africa. Increased productivity of fry and fingerlings with attributes of faster growth rates and better environmental tolerance is vital to ensuring fish food security in Africa. Fish culture today is hardly possible without the artificial propagation of fish seeds of preferred cultivable fish species. The need for the production of quality fish seed for stocking the fish ponds and natural water bodies has increase steadily.
Artificial propagation methods constitute the major practical means of providing enough quality seed for rearing in a confined fish enclosure waters such as fish ponds, reservoir and lakes (Charo and Oirere, 2000).
Apart from being able to obtain quality seed, the artificial breeding techniques can also be used to develop fishes superior to their ancestors by the methods of selective breeding and hybridization. The artificial breeding technique can achieve some times 65% or more of the eggs been raise to viable fingerlings compare to less than 1% survival rake on natural spawning. The issue in this artificial breeding is how to increase the productivity or the hatchability of eggs through quality or conducive water, pH and temperature management. The concept that every recipient water body has capacity to assimilate contaminants has been the basis for establishment of quality critical for aquatic life by different and national organization.
In other to ensure increased production of fry, (larva) and viable fingerlings. It is pertinent to evaluate factors that influences the hatchability of eggs.
These factors include:
Temperature:
Temperature is an important factor that affects the ability of eggs to be hatched. Temperature according to graham S, H, and Mohammed F.A (1995) the major abiotic factor controlling the rate of morphogenesis in fish. According to these authors the hatching is possible between temperature range of 150C to 350C. They however noted that the hatchability improved around 300C.
Onyeleye (2006) also noted that at average temperature at 27.66%, hatchability is about 27.84%.
pH:
pH is an important factors that affect the ability of eggs to be hatched, best pH for maximum hatching is 7.5 to 8.5. According to Ariole C.N. And Okpokwesili G.C. (2012) noted that average pH of 7.5 to 8.5 form best in hatchability of Dutch Clarias gariepinus.
Oxygen:
Maximum productivity require adequate supply of oxygen. The oxygen dissolved in water must be enough to ensure high productivity and the viability of the fingerlings.
Light:
Fishes are photophobic, therefore, they are sensitive to lights especially artificial light.
Water quality:
This factor is the major thrust of this study. The quality viability of eggs.
The aim of this study is to determine the use future as of bore-hole water. in the hatchery of Clarias gariepinus.
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