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Wallace’s catfish (Tetranematichthys wallacei) live in acidic, blackwater streams and small rivers with very slow water flow, where they lurk among submerged logs and branches. This catfish is a member of the driftwood catfish family (Auchenipteridae), a group of small to mid-sized fishes living in the rivers and lowland lakes of much of South America. Wallace’s catfish has a broad distribution in the Orinoco and Amazon drainage basins, where it lives among branches and trees that have fallen into streams and small rivers where the fish's mottled brown coloration allows it to blend in with the background. The two barbels below the lower lip extend forward and have elaborations at their tips which may serve as lures to attract smaller fishes and other prey. Males of the species have the spine of the dorsal fin on the top of the body elongate and stiffened. The barbels in front of the eyes are also lengthened and stiff and along with the spine on the dorsal fin help to embrace the female during spawning.
Wallace's Catfish is named after Alfred Russel Wallace, who, along with Charles Darwin, is most often remembered as the co-“discoverer” of evolution by natural selection. Starting in 1848, Wallace made large collections of plants and animals in the Amazon basin. Although his collections were all lost when the ship carrying him back to England caught fire and sank, he saved his notebooks and drawings, one of which clearly shows the species now named after him.
(Vari and Ferraris 2006)