Has been recorded from major river channels, smaller tributaries, and floodplain lakes, many of which comprise acidic, mineral-poor blackwater environments with brownish, tannin-stained water, although it has been observed to inhabit clear waters as well.

Many of its habitats lie within the Venezuelan and Colombian llanos, a vast, highly biodiverse system of tropical savannah grasslands, seasonally-flooded plains and forests covering an area measuring almost 600,000 square kilo…

Gasteropelecids are commonly-referred to as ‘freshwater hatchetfishes’ due to their heavily-keeled body shape which has evolved in such a way due to possessing an enlarged, heavily-muscled pectoral girdle, and which resembles the shape of a hatchet head.

They are sometimes said to be capable of propelled flight above the water surface by beating their pectoral fins but in fact this is not the case and was disproven by Wiest (1995) who used…

This species is also known as ‘Marilyn’s pencilfish’. It’s rarely traded in numbers and more often seen as bycatch among shipments of other species, particularly Paracheirodon axelrodi.

It can be identified by the following combination of characters: three dark lateral stripes (sometimes referred to as primary, secondary, and tertiary); nocturnal oblique bars relatively narrow, with the anterior bar reaching, but not extending past, the anterior base of the dorsal-fi…

The genus Apistogramma is among the most speciose of South American cichlid genera with around 70 species valid at present but many more awaiting description. In addition many species exist in two or more geographical colour forms which may or may not turn out to be distinct in the future. Hobbyists tend to label these with collection data if available in order to avoid mixing them and the potential of hybridisation.

For aquarists perhaps more useful are the subtle differences in colour pattern with P. simulans differing from both P. innesi and P. axelrodi in possessing a greener (vs. bluer) lateral stripe which covers more (vs. less) of the eye/head and extends to the caudal-fin base (vs. terminating anterior to caudal-fin base), a lesser (vs. greater) amount of relatively duller (vs. brighter) red pigmentation on the flanks.

The taxonomic history of all three species is complicated with earlier authors such as Géry (1960, 1977) ten…

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…

It was initially going to be described as Hyphessobrycon cardinalis by Myers and Weitzman (1956) but just before this was due to be published Schultz presented an alternative description in the hobbyist magazine ‘Tropical Fish Hobbyist’ and named the fish after the publication’s founder, Dr. Herbert R. Axelrod.

A significant proportion of the fish available in the aquarium trade are still wild caught or derive from community-led breeding projects such as Project Piaba in the middle Negro region, where this sp…

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…