Fish species composition is an important indicator of ecological health. This study aimed at assessing fish species composition and diversity along Buguma Creek, Rivers State, Nigeria.  The study was conducted for six months (January-June 2020) from three sampling stations. Water quality parameters and fish samples were collected and analyzed monthly. Fish species composition was determined with simple percentages.  Ranking method was used to ascertain the most abundant species. Fish diversity was evaluated using various diversity indices. The results indicated that all the water quality parameters (temperature, DO, pH, salinity, ammonia, nitrite, nitrate and water hardness/alkalinity) were not significantly different (p>0.05) in all three stations. Twenty (20) finfish species (belonging to 14 families out of which 11 were mono-specific) were identified in Buguma Creek, with the Sarotherodon melanotheron as the dominate species accounting for 39.42% (3304 individuals) of the total stock. For all diversity indices measured Station 3 recorded highest values followed by station 1 then station 2. Values at the three stations were: Shannon-Weiner index, H’ (S1=2.44; S2=1.94 and S3= 2.50); Pielou's index of evenness J, (S1=0.83; S2=0.65 and S3= 0.85); Simpson's Diversity index D, (S1=0.88; S2=0.77 and S3= 0.89); Margalef Species Richness index, M, (S1=2.76; S2=2.13 and S3= 3.06); Menhinick Species richness Index, d (S1=0.73; S2=0.23 and S3= 1.00).The dendrogram and diversity profiles showed that station 2 was different from stations 1and 3. However, the bootstrapping and diversity profiles showed that all the stations were similar. In conclusion, Buguma creek showed species diversity and with S. melanotheron being most abundant. In terms of biomonitoring, the abundance of S. melanotheron might be an indication of presence of environmental stressors.

This study evaluated the effects of multiple exposures of nutmeg and clove seed extracts on some electrolytes in two sizes of Clarias gariepinus. A total of six hundred (600) apparently healthy C. gariepinus, consisting of 300, 12 weeks old juvenile fish (mean length 19.66cm ± 1.17SD; mean weight 350.88g ±1.07SD) and 300, 24 weeks old adult sizes (mean length 44.66cm ±5.99SD; mean weight 1011.77g ± 54.99SD) were exposed repeatedly three times at one week interval to nutmeg and clove extracts as anaestheticsv in the laboratory. This study was carried out to assess changes in the electrolytes of fish during exposure to these extracts. The results obtained, indicated that the two anaesthetics caused a significant alteration (P <0.05) in the electrolytes which include Calcium (Ca²⁺); Sodium (Na⁺); Potassium (K⁺); Chloride (Cl^-­); and Bicarbonate (HC0₃^-) in the plasma of the exposed fish. Values of Ca^2+,   K^+, and Cl^-­ increased significantly (P<0.05) across different concentrations of anaesthetics, while Na⁺ and HC0₃ reduced. These alterations were more pronounced during the third exposure of C. gariepinus to these anaesthetics.