Some biological aspects and external parasitic infestation of fish species in Upper Awash River, West Showa Zone, Ethiopia

Abstract

A fishery is one of the important agricultural sectors for food security in Ethiopia. The resources are however highly decreasing due to unwise use and lack of scientific information for management. This study was aimed to assess some biological aspects and the external parasite infestation of fishes collected from the upper Awash River, Ethiopia. Fish samples were collected from five randomly selected sites using Frame net of 3mm mesh size.  Three fish species belonging to the Family Cyprinidae namely: Garra quadrimaculata, Garra dembeensis and Labeobarbus beso were identified. Dietary composition, GIS, fecundity, Length–Weight relationship, Fulton’s condition factor, sex ratio and ectoparasite infestation were assessed for the sufficiently collected fish species. The dietary composition revealed that G. quadrimaculata and L. beso were omnivorous. There was a significant correlation between the fish length and weight (r2=0.915 for G. quadrimaculata and 0.912 for G. dembeensis) with an allometric growth. The mean K value of females and males of G. quadrimaculata and G. dembeensis ranged between 1.31-1.36, 1.23-1.27 and 1.26-1.91, 1.35-1.98, respectively. The GSI value significantly varied among the study months. Fecundity of G. quadrimaculata ranged from 273 to 1056 eggs per fish with mean value of 692±270 eggs. There was a preponderance of females over males in most of the study months. The overall prevalence of Neascus (black spot) parasite was 18.09% and the intensity was highest (22 per individuals) on females. Less animal based food composition, poor body condition, early arrival at L50, less fecundity and the high infestation of Neascus parasite were the major problems identified in this study. Thus, effective management of the river basin and stocking the species into the aquaculture is very imperative for sustainable utilization of fish resources.