The energetics of rheotactic behaviour in Pterygoplichthys spp. (Teleostei: Loricariidae)
Station holding in Pterygoplichthys spp. was associated with a lower energy cost relative to similarly sized fishes that swam against the free stream current. Pterygoplichthys spp. was characterized by a low, stable mass-specific metabolic rate (c. 50 mg O2 kg−1 h−1) relative to subcarangiform swimmers that held position in the free stream, until it slipped backwards and burst swam against the current. Furthermore, the maximum range of the rate of oxygen consumption (aerobic scope) of Pterygoplichthys spp. was small relative to many non-benthic fishes.
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