Growth Patterns and Condition Factors of Some Freshwater Fish Species in Lake Erelu, Southwestern Nigeria

Abstract

Studies on length-weight relationship of fish provide valuable information on standing stock biomass for comparative growth studies. Information on growth patterns also remains an important tool for proper exploitation and management of population of fish species. The length-weight relationship (LWR) and condition factors of four dominant fish species in Erelu Lake, Oyo, Nigeria were therefore investigated. A total of 2663 specimens were caught between July, 2013 and March, 2015 using various mesh sizes of gillnets. Weights were taken to the nearest gram and length measured to the nearest centimeter using tabletop weighing balance and wooden measuring board, respectively. The sampled population was male dominated except for Raimas senegalensis. Total length was least in R. senegalensis (14.27±1.92) and highest in Sarotherodon galilaeus (18.30±1.92), while the least weight (51.26±29.53g) and the highest weight (85.60±42.99g) were obtained in R. Senegalensis and Oreochromis niloticus, respectively. The lowest growth coefficient (b) value (1.024) was obtained for O. niloticus while the highest (2.697) was recorded for R. senegalensis. This result indicates that all the investigated fish exhibited negative allometric growth. The mean condition factors (K) of the fish species ranged between 1.241±0.43 in S. galilaeus to 1.709±0.39 in O. niloticus. The condition factors fell within the range recommended for fresh water fish species in the tropics hence, Erelu Lake is suitable for the sustainable production of all the four fish species investigated. Therefore, the environmental condition of the lake should be maintained.