Fasil Degefu , Gashaw Tesfaye , Fikadu Tefera

National Fisheries and Aquaculture Research Center, Sebeta-Ethiopia, P.O.Box 64, Sebeta, Ethiopia
Author    Correspondence author
International Journal of Aquaculture, 2012, Vol. 2, No. 10   doi: 10.5376/ija.2012.02.0010
Received: 31 Oct., 2012    Accepted: 06 Nov., 2012    Published: 28 Nov., 2012

Degefu et al., 2012, Study on the Adaptability Status and Reproductive Success of Oreochromis niloticus L. (Pisces: Cichlidae) and Carp (Cyprinus carpio L., 1758) in a Tropic Reservoir (Fincha, Ethiopia), International Journal of Aquaculture, Vol.2, No.10 65-71 (doi: 10.5376/ija. 2012.02.0010)

The adaptability status and reproductive success of the introduced fish Nile Tilapia (Oreochromis niloticus L.) and common carp (Cyprinus carpio L., 1758) in Fincha reservoir, Ethiopia were studied on monthly basis from July 2006 to August 2007. Gill nets of different mesh size (60 mm, 80 mm, 100 mm, 120 mm and 140 mm, stretched mesh size) and beich sein (50 m long) were used to harvest the fish (a total of 645 fishes). Total length (L) and body weight (W) of both species were measured to the nearest 0.1 cm and 1g respectively. The results of the study showed that both fish species are adapted and have established successful breeding population in the reservoir. The size at first sexual maturity (L₅₀) for Oreochromis niloticus in Fincha reservoir was 21.8 cm for female and 24.5 cm for the male while L₅₀ was 37.5cm and 24.5cm for female and male Cyprinus carpio respectively. It was found that Oreochromis niloticus breeds throughout the year showing a peak breeding season in January and July in Fincha reservoir while Cyprinus carpio showed a peak breeding season between March and June. The length-weight relationships, total length (L) in cm; total weight (W) in g were calculated for O. niloticus (W=0.8×10^-2L^3.20; n=87; r²= 0.96) and C. carpio (W=1.4×10^-2L^2.97; n=558; r²=0.99) and showed a curvilinear relationship signifying the fish grow nearly isometrically. A significant seasonal variation (ANOVA, P < 0.05) was observed in the condition (K) of the fish coupled with the peak breeding season in Fincha reservoir. The relatively low values in the condition of the fish during January, March and July seems to coincide with the peak breeding season of the fish, which probably drains high energy for spawning. However, no significant difference was observed between sexes (ANOVA, P>0.05). Apparently, length frequency distribution of both species indicated that the fish population is normal fish population with no apparent problems of over exploitation. 

Breeding-season; Cyprinus carpio; Fincha; Oreochromis niloticus; Reservoir; Ethiopia