Physicochemical Properties and Biological Conditions of <i>Labeobarbus</i> spp. in Gumaro River, Lake Tana Sub‐Basin, Ethiopia

Abstract

ABSTRACT The Gumaro River is a key spawning habitat for endemic Labeobarbus species in the Lake Tana Sub‐basin. To support fisheries conservation, physicochemical conditions and biological characteristics of these threatened fishes were investigated monthly by sampling at multiple sites from August 2021 to January 2023. Fish were identified to the species level, and fork length, body weight, fecundity, gonadosomatic index and condition factors were recorded. Water quality parameters clearly showed seasonal variation. Phosphate (0.38–0.43 mg/L), nitrite (0.56–0.68 mg/L) and dissolved oxygen (7.2–8.0 mg/L) were highest over the rainy season, whereas ammonium concentrations (0.44–0.43 mg/L) reached the highest in the pre‐rainy period. On the other hand, sulphate (13.00 ± 2.53 mg/L), nitrate (1.84 ± 0.46 mg/L) and total dissolved solids (189.67 ± 28.86 mg/L) attained their peak values in the post‐rainy season. In total, 255 Labeobarbus specimens were analysed. The length–weight correlations demonstrated a very good linear relationship ( R = 0.83096). Different growth types were observed in the species, with Labeobarbus intermedius showing positive allometric growth ( b = 3.01) and Labeobarbus beso , Labeobarbus hybrid , Labeobarbus nedgia and Labeobarbus gorgorensis exhibiting negative allometric growth. Reproductive capacity differed between the species, with L. gorgorensis having the highest egg production, followed by L. nedgia . Most spawning activities were concentrated in September and October. Condition factors suggested that fish generally had a good physiological state. These findings highlight the ecological importance of the Gumaro River as a critical breeding habitat and provide essential baseline information for the conservation and management of endemic Labeobarbus spp.