This is a widely distributed group that superficially resemble eels - to which they are not related. There is a single opening on the underside of the head which is the gill opening and they breath air. These are extremely hardy fish that are able to live in floating meadows, swamps and habitats with poor oxygen. They are able to move across land if trapped in pools as the water level falls in flooded forest. They have a reputation as fierce predators and large specimens will bite. I think their aggression is exaggerated because of their superficial similarity to a snake which all Amazonians fear.
Identification: There are possibly two species of synbranchid within the Tarumã-Mirim. The common Brazilian form Synbranchus marmoratus and a second, possibly not described, species. Both are snake-like and unmistakable members of the genus. At present, it is impossible to be sure of the species we are collecting within the leaf-litter. Specimens from forest streams are usually small and are probably juvenile. Habitat: Burrowing within leaf-litter Abundance: Common, an average density of 1.1 individuals per square meter of litter surface area. Food: Both forms are predatory, feeding while juvenile on insects and prawns.
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Synbranchus species - Small juvenile eel caught in submerged leaf litter in a blackwater stream
A large Synbranchus species caught in flooded forest