the Rockettail Pencilfish (Nannostomus eques), also called the "hockeystick pencilfish" or the "diptail pencilfish", is a small freshwater species of pencilfish. This particular species is defined by their slim, thin "pencil-like" bodies, a bright white horizontal stripe, and a thick dark brown/red horizontal stripe. The dark brown/red stripe continues through the bottom half of the fish's tail.
This surface-dwelling fish is unique, in the sense that they swim in a vertical position with their heads up. They are a very shy shoaling fish, and do best in groups of 6 or more. They spend a lot of time hiding, especially if kept in too small of a group. A shoal of these fish can live comfortably in a 15-gallon aquarium. They live for 4 years on average and grow to be 2 inches long.
These fish prefer water temperatures in the low 70's through the low 80's, and are generally quite hardy. They do well in a neutral pH, but generally prefer slightly acidic water. They prefer an aquarium with many hiding places, and a secure-fitting lid is recommended as they may be prone to jumping when frightened.
These fish are primarily carnivorous. They will enjoy small frozen and live foods such as baby brine shrimp, daphnia, and bloodworms. They will also accept crushed fish flakes, and micropellets.
Rockettail Pencilfish are very timid. They are a docile animal that will not bother your other community fish species, and can be kept with any other moderately slow docile fish species. Do not keep them with any fish large enough to eat them, or any fish species that may be considered too energetic (such as danios or large tetra species).
(Photo credit "Wikipedia")