Boulengerella differs from Ctenolucia, the only other genus currently contained in the family Ctenolucidae, by a series of derived features including possession of 87-124 (vs. 45-50) lateral line scales, presence of a strongly (vs. weakly) developed fleshy appendage at the tip of the snout and absence (vs. presence) of fleshy flaps on the lower jaw.

Within the order Characiformes the family Ctenoluciidae is also distinguished by a set o…

It’s a member of the nominal G. surinamensis ‘group’ of closely-related species within the genus and can be identified by a combination of characters including: presence of dark preopercular markings; seven parallel vertical bars on each flank (normally visible only when the fish are stressed, spawning or preserved); vertical bars four and five meet in such a way that they form a ‘Y’ shape; dark lateral spot positioned within the third vertical bar; caudal fin reddish with variable pattern of iridescent blue spots and stripes.

At least two colour forms have been traded, one of which is more intensely-coloured and has been referred to as H. sweglesi ‘red’ or ‘rubra’. The bright red pigmentation is retained in long-term captive specimens, suggesting that it is not considered to be an artefact of diet, but we suspect it might reflect conditions at the collection locality with the reddest fish putatively inhabiting blackwater and plainer forms clearwater environments. Zarske (2014) found the two forms to be identical in terms of morphology an…

S. daemon is relatively common in the aquarium trade but is by no means easy to maintain, with particular attention to space, diet, water quality, and chemistry required in order for it to thrive.

It can be distinguished from other members of the genus by possessing two dark blotches on the flank and a prominent ocellus at the caudal-fin base. Among the named species it is most similar to…