Feeding habits of the Nile perch, Lates niloticus (L.) (Pisces: Centropomidae) in Lake Chamo, Ethiopia
AbstractDiet composition and ontogenetic diet shift of the Nile perch, Lates niloticus (L.) were studied from 411 fish samples (1.9 cm to 192 cm TL) collected from February 1995 to May 1996. Most fish samples (n=221, 53.8%) had empty stomachs. Except the two smallest fry (1.9 cm and 2.3 cm TL) fish samples (n=188) that contained food in their stomachs consumed only fish. The cyprinid fish Labeo horie (Heckel) was the most important prey organism of juvenile and adult L. niloticus and occurred in 49.4% of the stomachs examined, constituted 38.02% of the total number and 70.44% of the total volume of the prey. Oreochromis niloticus (L.) occurred in 22.35% of the stomachs accounted for 19% of the total number and 24.82% of the total volume of food consumed. Hydrocynus forskahlii (Cuvier) occurred in 14.12% of the stomachs, constituted 9.92% of the total number and 2.72% of the total volume of prey consumed. Cannibalism was observed in 19.4% of juvenile fish (n=62, 48.5–73.2 cm TL) and smaller L. niloticus constituted 26.1% of the total volume of food consumed within this size range. H. forskahlii, O. niloticus and L. niloticus were the main prey of fish <90 cm TL while L. horie was important prey of fish >90 cm TL. Based on index of relative importance (IRI) L. horie was the most important prey (5359) followed by O. niloticus (979), L. niloticus (392) and H. forskahlii (178.5). Fry and fingerlings of L. niloticus (n=20) ranging from 1.9 to 7.1 cm TL were caught using a beach seine of 6 mm mesh size. The two smallest fish (1.9 cm and 2.5 cm TL) had eaten insect larvae while the remaining 18 fish had all eaten 1–3 fry of O. niloticus that ranged from 0.8 to 1.9 cm TL.
Key words/phrases: Cannibalism, diet composition, Lates niloticus, ontogenetic diet shift, predation
SINET: Ethiopian Journal of Science Vol. 28 (1) 2005: 61-68