Length-Weight Relationship, Condition Factor and Natural Diet of Hyperopisus bebe occidentalis and Brycinus macrolepidotus in Ikere Gorge, South-West, Nigeria

Abstract

This study was conducted to determine the Length-weight relationship, Condition factor and Feeding habit of two commercial fish species Hyperopisus bebe occidentalis and Brycinus macrolepidotus in Ikere Gorge. A total of 561 samples (276 Hyperopisus bebe occidentalis and 285 Brycinus macrolepidotus) were caught from experimental gill net between October 2015 to November 2016 across five fishing site. Sex ratio show significant different p <0.05 across all location in favor of females in Hyperopisus bebe occidentalis. Male dominancy was recorded for Brycinus macrolepidotus in most fishing site with chi square value of 18.33. Growth pattern for Hyperopisus bebe occidentalis showed positive allometric in three of the sampling locations (Oyo junction, Apata and Spillway) with b value >3 and poor environmental condition less than 1 in all the locations. Brycinus macrolepidotus observed negative allometric growth pattern in all the sampling location with better ecological condition (K values >1). Stomach index expressed as percentage indicate that Brycinus macrolepidotus had the highest percentage of empty stomach (35.44%) while Hyperopisus bebe occidentalis recorded low value of empty stomach (0.36%). Size class food composition by Brycinus macrolepidotus and Hyperopisus bebe occidentalis showed a wide spectrum of items ingested at the various stages of life. Broad classification showed that Juveniles fed on Desmidiaceae as dominant item (34.91% and 32.03%), followed by Chlorophyceae (31.10% and 33.95%); Sub-adult fed on Chlorophyceae (28.38% and 39.80%), followed by Protozoans (18.96% and 19.68%), while Adult fed on Rotifers (28.91% and 13.17%) followed by Bacillarophyceae, (17.07% and 18.63%). The present of Sub adult and adult was notice in Hyperopisus bebe occidentalis, Green algae (19.96% and 17.92%) follow by Diatoms (17.50% and 24.37%); while in Adult Green algae (19.89% and 19.23%) follow by Diatoms (18.21% and 21.41%). This shows that as the fish species increases in size food item ingested also increase. Base on the identify food items in the stomach of both species Brycinus macrolepidotus is classified as Omnivore while Hyperopisus bebe occidentalis indicate Herbivore nature.