Introduction All ovr the universe, global climate change is being encountered and its physical impacts are felt everywhere (Shakoor et al., 2015). The varying weather patterns affect both the quantity and quality of water resources available for irrigation, fish farming, and power generation. Regrettably, it's also bringing about increasing temperatures, giving rise to both negative also as positive impacts on fishing and fish culture systems consistent with the region and latitude (Magawata and Ipinjolu, 2014). thanks to rise in universal climatic change, the water level structure in most freshwater bodies will probably adjust as a results of drought or flood effect. Patino and Thomas (1990), Nagahama et al. (1995), reports that ovarian follicle maturation in fish includes maturational processes within the nucleus and cytopolasm of the oocyte. Such processes are: germinal vesicle migration (GVM), switch in follicular secretion from C18 to C21 steroids, acquisition of oocyte maturational competence (OMC) and therefore the ability of the oocyte to resume meiosis in response to a progestin. This study was administered to assess the impact of water level variation caused by global climate change on ovarian recrudescence in African catfish (Clarias gariepinus) female broodstock. Materials and methods Experimental Design Twelve tanks were used for the experiment. The fishes were randomly distributed into the twelve (12) tanks (1m x 1m x 0.9m) at a consistent rate of two (2) broodstock per tank. The experimental tanks were organized in three locations namely: laboratory, outdoor and greenhouse. Each treatment location had two volumes of water (20L and 10L). there have been thus three (3) treatments and three (3) replicates. a complete of twenty-six (26) fishes were stocked within the three (3) treatments x three (3) replicate experiments. The fish in each tank were manually fed 2% of their weight in two regimes per day at 9.00 hours and 15.00 hours for 49 days in static water. Fish were weighed every fortnight and therefore the quantity of feed adjusted accordingly. The effect of water level variation on the fish ovarian development, growth and maturity was investigated using histological procedures. Data Collection and Analysis At the start of the experiment, the gravid fish (female broodstock) were injected with hormone and stripped off all the eggs. there have been fed for five weeks (for first sampling). One fish from each treatment group was dissected and therefore the refore the gonad removed and at the 7 weeks (for second sampling) one fish from each treatment group was also dissected and the gonad removed to see the gonadal development of the fish. The gonads were weighed and preserved in 10% formol saline for further analysis. Histological procedures Gonad maturity decided histologically by means of sunshine microscopy. The developmental stages of the ovaries were determined for every treatment. Oocytes were classified by developmental stage adapted from Bromage et al. (1987). Gonad samples were fixed for 24-48hrs in Bouins solution then subjected to histological processing.
