Despite its patent unsuitability as an aquarium subject attractively-coloured juvenile specimens of this species are traded in quite large numbers, although the scarcity of privately-maintained adults would suggest that most fail to reach their potential. The striking, spotted patterning also disappears as this species matures, and since it also becomes increasingly bellligerent with age it can only be recommended to owners of the largest private aquaria or tropical ponds. There exists an albino…

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Wild populations vary in colour pattern depending on origin, and some populations have previously been described as distinct species.

A form from Peru has a particularly silvery body colour, for example, while another, marketed as ‘super red’ possesses an unusually long red stripe on the body, extending much of the length of the dark central stripe. A population from around Boa Vista in the rio Branco system, Pará state, Brazil has an ocellus o…

This species is quite rare in the aquarium hobby and is not often available in numbers, more often being exported as bycatch among shipments of the congener N. eques.

Following Weitzman and Cobb (1975) it can be diagnosed by the following combin…

There also exist a number of minor differences in colour pattern between populations. For example some Peruvian forms have yellow pigmentation on the body and fins, and those from Guyana and Suriname possess a short red stripe on vertical scale rows 6-9, above the central dark stripe on the body.

Rio Negro forms have a similar red stripe but overlapping the central dark stripe and extending along most of the flank, while a form from Colombia has an elongate red stripe which is broken in two beneath the dorsal-fi…

There are a few geographical variants of this species available, which differ in colour, patterning and less commonly, size. These should not be mixed in aquaria, as they may hybridise. The differences are so apparent between some of these forms that they may well turn out to be different species in the future….

This species has been referred to the genera Poecilobrycon and Nannobrycon in the past and in the aquarium hobby is also known as ‘rocket’, ‘brown’, ‘brown-tailed’, ‘diptail’, or ‘tubemouth’ pencilfish.It’s a popular aquarium fish and has an interesting oblique swimming-style, a behavioural trait shared only with N. unifasciatus among congeners.

In the original description the colour pattern is given by Steindachner as a brown lateral stripe exte…

This is the type species of the genus, fairly ubiquitous in the aquarium trade, and represents an excellent choice for the newcomer to fishkeeping since it’s less demanding than most congeners. It’s sometimes referred to as ‘Beckford’s pencil fish’ or ‘brown pencilfish’.

Don’t worry if your fish look different when you switch on the aquarium lights after dark or in the morning as like most Nannostomus species it assumes a cryptic, vertically-barred colour pattern at ni…

Unfortunately the prisitine environment form where this fish comes is being threatened by overfishing (much of it for the aquarium trade) and industry, with an oil development being built at one end of the lake during the 1990s. M. lacustris has therefore been given "vulnerable" status on the IUCN red list. The lake was designated a Wetland of International Importance in 1998, as both it and the Kikori Basin where it lies contain some of the earth's greatest biodiversity in terms …

This beautiful rainbow is not often seen in the hobby. It can be identified by the fact that the middle rays in the dorsal and anal fins are longer than the other fin rays. This feature is usually associated with the closely-realated Glossolepis genus of rainbowfish….