Olopade OA, Rufai OP. 2014. Composition, abundance and diversity of the Family Cichlidae in Oyan Dam, Ogun State, Nigeria. Biodiversitas 15: 195-199.This study was conducted to determine status of the family Cichlidae in Oyan Dam, Nigeria, during the wet and dry seasons of 2011. Samples were collected using multi-mesh gillnets ranging between 30 mm to 80 mm. Simpson's Diversity Index was used to determine the species richness, while dominance and evenness were given by Shannon's index. A total of 547 individuals were caught from Imala (S1) and Ibaro (S2) sites of the dam. Species collected include Sarotherodon galilaeus (42.60%), Oreochromis niloticus (17.92%), Tilapia zillii (25.41%), Hemichromis fasciatus (10.61%) and Tilapia mariae (3.48%). Juveniles and sub-adults and adults were among the catch, the sizes were as big as 12.85±0.29cm SL, 109.22±6.00g BW in Tilapia zillii and small as 6.09±0.05cm SL and 8.07±0.15g BW in Hemichromis fasciatus. The diversity indexes showed that the diversity of Cichlids was lower in the two sites observed in Oyan Dam. The estimates of diversity indexes showed lower value for site 1 (0.284) than for site 2 (0.294); Simpson's diversity index was 0.716 for site 1 and 0.703 for site 2 while reciprocal indexes for site 1(3.521) was slightly lower than site 2 (3.367). Shannon-Wiener's Index recorded in the site 1 (1.36) was slightly lower than site 2 (1.37). Pielou's Index value recorded for site 1 was 0.845 and 0.852 for site 2. Sarotherodon galilaeus, Oreochromis niloticus, Tilapia zillii and Tilapia mariae exhibited a positive allometric growth pattern while only Hemichromis fasciatus showed a negative allometric growth.

The aim of this study was to determine and compare the proximate composition of Oreochromis niloticus and hybrid Tilapia, from Oyan Lake. Parameters proximate composition which includes protein, lipid, ash and moisture content were estimated. The average moisture content for O.niloticus was in range of 81.11 to 81.67% and 80.01 to 80.17% for hybrid Tilapia. %. Results revealed that there was a significant difference in the mean protein values of O.niloticus and hybrid tilapia with the females of the two fish species were observed to have significantly higher (p <0.05) crude protein content than their male counterparts. The fat content values were low but significantly different (p<0.05) between the hybrid Tilapia and O.niloticus. Ash content ranged from 1.24 to1.48% for the O.niloticus and 1.30 to 1.24% for the hybrid Tilapia.

This research was undertaken to find out the levels of five heavy metals (Cu, Fe, Mn, Pb, and Zn) in the muscles of eight fish species from Epe Lagoon. The levels of heavy metals were determined by atomic absorption spectrophotometry after digestion of the samples using Kjldahl heating digester. The heavy metal concentrations among the fish species were statistically dissimilar (P < 0.5). The heavy metals of Pb, Fe, and Mn were above the FAO/WHO agreeable limits for human consumption.

Fish catch composition of some selected small scale fishing gears (gill net, cast net, beach seine and long line) were investigated in Bonny River, Rivers State, Nigeria from August 2014 to January 2015. A total number of 25 fish species from 18 families were recorded during the study. The Mugilidae with only one species constituted the dominant family while Cichlidae, Lutjanidae, Clupeidae, had three species and Scianidae had two species of fish caught and the remaining families had one species each. Mugil cephalus constituted 28.48% of the total catches followed by C. nigrodigitatus (22.48%). In the dry season M. cephalus forms the major component landings (32.65%), followed by C. nigrodigitatus (26.53%) and S. galilaeus (12.24%) while in the wet season M. cephalus (31.06%), C. nigrodigitatus (18.63%) and T. zillii (11.80%) were the dominant fish species. Cast net was the most efficient fishing gear while gill net was the least efficient. The comparison analysis between the wet and dry seasons using t-test showed no significant difference between dry and wet seasons (t = 0.092, P > 0.05).