| Summary: | Adaptation Modes of four Species of Labeo (Pisces, Cyprinidae) to Occupy Different Ecological Niches in the Pool Malebo of the Congo River in the Democratic Republic of the Congo
The aim of this study was to understand the possible relations between anatomy, morphology and environmental factors of the ecological niches of different Labeo species in the “Pool Malebo” of the Congo River in the Democratic Republic of the Congo. Fifteen morphological parameters were measured on 15 adult specimens of 4 species of Labeo: L lineatus, L weeksii, L nasus and L sorex and compared to 13 environmental variables in 6 fishing sites of these fish. Two types of sites were identified and explored: 4 lentic sites (Japon, Mipongo, Molondo and Tandalitoko) and 2 lotic sites (Kinsuka and Ngamanzo). The speed of the stream, the depth and the bottom substratum are the main factors which induce fish adaptations. The reduction of the eye size and the gaseous bladder, the large pair flippers in ventral position and the small gills allow L. sorex and L. nasus to adapt to lotic areas. On the other hand, big eyes, a long gaseous bladder divided into two sections, lateral pair flippers and wide gills help L. lineatus and L. weeksii to fit in lentic areas.
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