Diversity and Some Biological Aspects of Fishes From a River in the National Park of Ethiopia

The Denkoro River is the largest river in Borena Sayint National Park (BSNP) of Ethiopia. Many studies have been conducted on the terrestrial biodiversity of the park. However, there are no baseline data on the fish biodiversity of the park. Therefore, this study aimed to assess the diversity, determine the biology of the dominant fishes, and compile baseline data. Fish specimens were collected using gillnets (4, 6, 8, 10, and 12 cm stretched mesh sizes), monofilaments (5, 10, 15, and 20 mm mesh size), and hook and lines. Fish samples in the Denkoro River were collected in wet (September) and dry (December) seasons, 2022. A total of 398 fish specimens were collected from three sites in both seasons. Five fish species, Labeobarbus intermedius, Garra dembecha, Clarias gariepinus, Labeobarbus beso, and Oreochromis niloticus, were identified from the river. The diversities (H′) of fish species in the Wachau, Buke, and Kernemariam sites in the dry season were 1.45, 0.95, and 0.64, respectively. During the wet season, fish species diversity was lower than that in the dry season, with Shannon diversity indices of 1.33, 1.18, and 0.93 at the Wachau, Buke, and Kernemariam sites, respectively. L. intermedius was the most abundant species, with 42.9% of the total catch. The length–weight relationships of L. intermedius and L. beso followed a curvilinear pattern, described by the equations TW = 0.005TL^3.12 and TW = 0.01TL^2.94, respectively. In all sites, females were more numerous than males and statistically significant (Chi-square, p < 0.05). For sustainable fish conservation and development, further research on fishing activities, feeding habits, and fish biology is needed. Important management measures such as regulated fishing activities, habitat restoration, and spawning ground protection should be performed in the area.