Growth analysis and sex ratio of fish species from the Ovia River, Edo State, Nigeria

Abstract

This study investigated the length-weight relationships, the condition factor, and the sex ratio of Hemichromis fasciatus, Synodontis nigrita, and Tilapia zillii in the Ovia River, Edo State, Nigeria. Fish specimens were collected with the assistance of artisanal fishermen using fishing traps, cast and gill nets of various mesh sizes from February to April 2021. Taxonomical identification, morphometric measurements, and macroscopic examination of the fresh gonads were carried out. The linear regression equation was used to determine the relationship between fish length and body weight, while the condition factor and the sex ratio were analysed using standard techniques. Length-weight relationship (LWR) showed a significant (p < 0.05) correlation and the growth exponent b = 2.973, 2.340, and 2.565 for H. fasciatus, S. nigrita and T. zillii, respectively, indicated a negative allometric growth pattern. Mean condition factor values ranged from 2.34 to 5.68 and was indicative of good health condition for the fishes. Sex ratios did not differ significantly (p > 0.05) from the one male to one female distribution in H. fasciatus (1:1.11), S. nigrita (1:0.89), and T. zillii (1:0.93). The study has provided information on some aspects of the fish biology of Hemichromis fasciatus, Synodontis nigrita, and Tilapia zillii in the Ovia River, and these data are helpful tools for fisheries management and conservation of freshwater fishes.