Brooding and nest-maintenance behaviors of the bagrid catfish Auchenoglanis occidentalis (Valenciennes, 1840) were studied in the southern end of Lake Tanganyika. We observed huge saucerlike nests, 1.2–3.8 m across, on the fine sand bottom of the littoral zone. The lowest parts of the nests were covered with an accumulation of coarse particles consisting mainly of gastropod and bivalve shells and shell-fragments, which the catfish sifted out from the sediment. Broods were buried within the shell accumulation and tended solely by males for up to two weeks until the juveniles were motile. Brooding males spent most of their time fanning the pectoral fins and undulating the posterior body. These movements resulted in water flow over the broods, which might serve to prevent oxygen deficiency. They did not act aggressively against intruding potential brood-predators. Nest distribution and relationships between nest size and shell content in the sediment suggest that nest site selection and nest size are determined by the shell availability in the sediment.