MARGINATUS PENCIL – 小红铅笔鱼

Dwarf pencilfish (Nannostomus marginatus) is a freshwater aquarium fish, one of the smallest representatives of the Lebiasinidae family, Characiformes unit. Due to breeding challenges and the small number of eggs they lay, dwarf pencilfish can’t be considered popular tank fish. Nowadays, they are seldom encountered in aquariums, even though they are perfect for keeping in nano aquariums which are currently gaining popularity.

It has a slim, spindle-shaped, elongated body, small mouth, and quite large eyes. It has a transparent tail fin. Its unpaired fins, except for the tail one, are more or less red-colored with dark edges. Abdominal fins are red, and pectoral ones are transparent; the tail fin has some grayish tint with rounded edges and not deep indentation. The fish doesn’t have a fatty fin.

An interesting feature of Nannostomus marginatus is its night coloring. In some species, the latter differs dramatically from their day coloring, and it may surprise an inexperienced observer.

The fish stripes just get paler at night, and the central stripe becomes dashed instead of the full line. It is interesting to note that the female demonstrates coloring similar to the night one at the day as well. This happens in response to the male’s attention if she isn’t ready to spawning yet. After this, the male becomes more patient and waits till the female is ready. This way, she at least partially escapes the unwanted attention.