Length-weight relationship and condition factor for five common fish species in a recently constructed reservoir (Tugwi-Mukosi Dam) - Zimbabwe

Abstract

Tugwi-Mukosi is a recently constructed reservoir in the Masvingo Province of Zimbabwe. The objective of the study was to estimate the length-weight relationship (LWR) and condition factors (K) of five freshwater fish species collected from the dam. Three hundred eighty-seven fish samples were caught by gill nets and sein between January and September 2021. The estimated exponent value b varied between 2.814 and 3.228 among the fish species. The b values indicated that three species (Oreochromis niloticus, Coptodon rendalli and Micropterus salmoides) followed negative allometric growth (b < 3). In contrast, Clarias garipinus showed isometric growth (b = 3), while Oreochromis mossambicus exhibited positive allometric growth (b > 3). More than 94% (R2 > 0.94) of the weights (responses) variations were explained by the models, so the models fit the data well. The K values of all the fish species, except for C. gariepinus, ranged between 1.3 - 2.2; this indicates that these species are doing well in the reservoir. This observation suggests that Tugwi-Mukosi currently provides a favourable habitat for the fish species. The current study's findings will give valuable baseline data for assessing the status of fish populations and conducting ecological surveys for future fish conservation and management.