Abstract: Reviewed literatures revealed Oyster shell as a potential adsorbent material that can be used to control pollution in groundwater. The study examined the impact of exposure and duration of exposure of water (tagged C-0) that was reported incapable of supporting fish egg hatching to quantities of crushed Oyster shell (COS) for curative to use the water for fish seed propagation. The water was studied alongside proven convenient water for fish egg hatching (F-0) in the study area. The water (C-0) in 5 separate containers was exposed to COS at 1.08g/l for 13, 9, 5 and 3 days and 0.80g/l for 3days prior to use for seed propagation. The five experimental treatments were studied alongside C-0 and F-0 with zero shells. Water quality conditions of each treatment were monitored during the study. Fertilized Clarias gariepinus eggs were incubated in each treatment in triplicates. Eggs were monitored for fertilization, hatchability and larval growth.
The pH and hardness in F-0 (6.63, 63.3mg/l) and C-0 (4.47, 104.0mg/l) were significantly different (P<0.05). The pH of C-0 increased from 4.47 to 8.45 while the hardness increased from 104.0mg/l to 153.3mg/l when the water was exposed to crushed Oyster shell at 1.08g/l for 9 days. When the exposure duration was extended to 13 days, the pH did not change; however the hardness increased to 169.3mg/l (Table 1). Egg hatching and larval development in C-0 were improved with COS. Fastest growth was recorded when it was exposed to COS at 1.08mg/l for 3 days (Table 2). The improvement could result from the ability of COS to induce pH increment of the acidic water due to its high calcium content.
Key words: Clarias gariepinus, Curative, Egg hatching, larval development and Water quality