This species is sometimes traded as ‘Espei’s’, ‘four-barred’ or ‘banded’ pencilfish and is sought after in the aquarium hobby, though normally quite expensive to buy.

It’s most-easily identified by its unique colour pattern of 5 dark, vertically-orientated bar-like markings on each flank, this in direct contrast to the horizontal stripes seen in other congeners…

Native to the central Amazon basin with records existing from the Madeira, Branco, Trombetas, and Tapajós river drainages, plus the Rupununi basin in Guyana. Although an affluent of the rio Essequibo and thus not officially part of the Amazon basin, the latter is connected to the rio Takutu, a tributary of the upper rio Branco, during the annual wet season.

Type locality is given by Fowler as ‘Rio Madeira about 200 miles east of W. Long. 62°20′, Brazil’.

This is the smallest member of the genus and rarely traded in numbers, though it’s a relatively common contaminant among shipments of wild fishes from Manaus. Unlike other Nannostomus spp. it does not exhibit a specific colour pattern of spots or bars at night-time, rather displaying an overall paleness.

The family Lebiasinidae is included in the order Characiformes and sometimes split into the nominal subfamilies Lebiasininae a…

This species is a member of the putative A. nasutus group of closely-related species within the genus alongside A. nasutus, A. maculipinna and A. isalineae.

These are all characterised by possession of two dark, longitudinal stripes, one running from the tip of the snout to the base and the other from the posterior edge of the lower maxilla to the underside of the caudal peduncle.

This species is a member of the putative A. nasutus group of closely-related species within the genus alongside A. nasutus, A. maculipinna and A. isalineae.

These are characterised by possession of two dark, longitudinal stripes, one running from the tip of the snout to the base and the other from the posterior edge of the lower maxilla to the underside of the caudal peduncle.

An obligate piscivore capable of consuming quite large prey in relation to its body size although it tends to focus on smaller prey such as tetras and related species.

Newly-imported specimens may refuse to accept anything but live fishes although most can be weaned onto dead alternatives once they recognise them as edible, and some even learn to accept dried foods.

An obligate piscivore capable of consuming surprisingly surprisingly large prey.

Newly-imported specimens may refuse to accept anything but live fishes although most can be weaned onto dead alternatives once they recognise them as edible, and some even learn to accept dried foods-

Like the vast majority of predatory fishes this specie…

This species is not normally aggressive towards conspecifics with juveniles in particular exhibiting a marked schooling instinct.

Older individuals tend to be more solitary but still group together from time-to-time, and it’s best maintained in numbers of four or more.

One important point to note is that acestrorhynchids are can…

This species is traded under various other names including ‘red arc pencilfish’, ‘Peruvian red pencilfish’, ‘ruby red pencilfish’, ‘red pencilfish’, and Nannostomus cf. marginatus ‘red’.

It was initially described as a subspecies of N. marginatus but can be identified by the following combination of characters: pronounced sexual dimorphism with adult males exhibiting bright red pigmentation between the central…

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

The most recent diagnosis of the species appears to be that giv…