Morphometric Analysis and Length-Weight Relationships of Arnoldichthys spilopterus and Raiamas senegalensis in a Tropical Man-Made Lake, Northeastern Nigeria

Background and Objective: The knowledge of growth variations, population structure, and condition of endemic fish populations offers valuable information in their conservation and management for sustainable use. This study, thus, investigates the morphometry and length-weight relationships of two indigenous ornamental fish, Arnoldichthys spilopterus and Raiamas senegalensis, in Lake Alau. Materials and Methods: Fifty specimens each of A. spilopterusand R. senegalensiswere caught, weighed, and nine morphometric features were examined. Length-weight relationships and condition factors were calculated for each species following standard methods. Data collected were analyzed using descriptive statistics, linear regression, and correlation analysis. Results: The sampled fish had a mean size of 12.66±3.07 cm (33.06±16.81 g) in A. spilopterus and 12.65±1.55 cm (17.68±8.62 g) for R. senegalensis. Results indicate a significant positive correlation between morphometric characteristics and varying degrees of interdependence with total length in both species. The regression coefficient “b” value of A. spilopterus population (2.49) shows negative allometric growth, while R. senegalensis (3.33) showed positive allometric growth. The condition factor varied from 0.82±0.09 in R. senegalensis to 1.54±0.36 in A. spilopterus, indicative that the latter fares better than the former in the Lake. Conclusion: The findings suggest that the habitat provides optimal growth conditions for these species, but certain environmental factors might be responsible for the low condition factor in Silver fish.