An experiment was carried out to assess the morphometric measurements and meristic counts of black jaw tilapia, Sarotherodon melanotheron (Ruppell, 1852) from Buguma, Ogbakiri and Elechi creeks, Rivers State, Nigeria. The study was done to determine racial variations between this specie in the three environments. Fifty specimens were collected monthly from each location between April and June 2017. The results revealed that they were phenotypically separable populations of the same species. Significant differences (P < 0.05) were recorded in body depth, and caudal peduncle length in each month between the fish sampled from Buguma and other two creeks, which were suggested to have occurred as a result of difference in the environmental conditions in the three creeks. The results also implied that fish from Buguma creek could be preferable as brood stock for breeding programmes.

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This study investigated the effects of formulated and commercial diets as starter feeds on the performance of Clarias gariepinus larvae in the hatchery. Two hundred larvae were randomly distributed in experimental tanks and were fed with a commercial diet Aqualis and Special formulated feed (poultry feed + fishmeal + vitamin C + premix) for 21 days. The result obtained revealed that there was no significant difference (P>0.05) in the physico-chemical parameters in all treatments. Total heterotrophic bacteria, Vibro, Total coliform and Salmonela/ Shigella were identified in the microbial analysis of the fish waters in all treatments. The total heterotrophic, and Vibro counts in the tank waters were significantly higher in specially formulated diet than Aqualis starter feed. Total coliform count and Salmonela/Shigella were less than thirty (<30) in all the water samples. Fish fed Special feed had a higher survival rate than Aqualis. Special feed was also higher in length increase of larvae (8.96 ± 7.11 mm), than the larvae fed with Aqualis. There was steady reduction of the microbial flora as the fish became older. The weekly results showed that condition factors were less than one, in all the treatments, at the end of the third week.

One hundred and eighty (180) mudskipper (Periophthalmus papilio) of equal size (mean length 18.74 ± 2.64cm and mean weight 156.68 ± 1.81g) were exposed to different concentrations (0.0mg/l-control, 5.0, 10.0, 15.0, 20.0 and 25.0mg/l) of sodium bromide a biocide, to determine the Behavioural responses of opercula beat frequency (OBF), tail beat frequency (TBF), 96 hour lethal concentration (96h.LC 50 and median lethal time (MLT 50). The result obtained indicated that P. papilio showed initial stress responses such as increased opercula ventilator rate, erratic swimming and gasping for air. The pattern of response of TBF to time and concentrations of the biocide was irregular, whereas that of OBF tended to decrease with increase in time, but increased with increase in concentrations. Also cumulative mortality values increased with exposure time and concentrations.

This study aimed to investigate the effect of different concentrations of physiological saline (0, 3, 6 and 9 g/l as control) on the reproductive performance of Clarias gariepinus within 7 days of induced breeding. At the end of the experiment, there were significant increases (ANOVA, p>0.05) in fertilization, hatching and survival rate with an increase in physiological saline concentration up to 6 g/l. Values were (mean ± standard deviation, SD, %) 94.3 ± 1.1, 88.8 ± 3.0 and 78.7 ± 2.3 for fertilization, hatching and survival rate respectively. The physico-chemical parameters were measured and values were within the ideal range for C. gariepinus production. Overall, the results indicated that milt prepared in 6 g/l physiological saline concentration is the most ideal for fertilization, hatching and survival of C. gariepinus larvae