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…