The ogre catfish: prey scooping by the auchenipterid Asterophysus batrachus

Jansen Zuanon and Ivan Sazima

aqua, International Journal of Ichthyology, pp. 15-22, Volume 10, Issue 1 – June 2005


The catfish Asterophysus batrachus (Auchenipteridae) has a huge mouth gape and is able to ingest very large prey. However, how it catches and positions such prey in its stomach remains unrecorded. We studied the predatory behaviour of A. batrachus under aquarium conditions and found a novel feeding mode for piscivorous Neotropical catfishes. Asterophysus batrachus uses its cavernous gape in a remarkable way, scooping up large unaware prey headfirst, then taking advantage of the fleeing response to further the prey’s advance into its stomach. Positioning of the prey results from additional escape movements into the very distensible belly of the catfish. The prey ends up folded in the stomach with its head and tail pointing towards the head of the predator. A fasting catfish occasionally takes in water, bulging its belly considerably (“belly ballooning”). After a while the fish expels the water entirely, along with a little mucus and a few small fragments of food. The wrinkled belly quickly regains its former shape. Because of its huge mouth, ability to swallow large prey and overall appearance, we name A. batrachus the ogre catfish.

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