Spot-tail Dartfish

The Spot-tail Dartfish is a delicate and understated member of the Ptereleotris genus, distinguished by a characteristic dark spot on the caudal peduncle (the narrow body region just before the tail fin) that serves as its primary identifying feature. The body is a soft, translucent blue-white with subtle iridescent reflections, and the fins may display faint pinkish or lavender tones. At around 3 inches maximum length, it is one of the smaller dartfish species, making it well-suited for nano and mid-sized reef aquariums.

In the wild, Ptereleotris uroditaenia is found throughout the Indo-Pacific, inhabiting sandy slopes and rubble zones adjacent to coral reefs. Like other Ptereleotris species, it hovers in small groups above the substrate, picking zooplankton from the water column. The species maintains burrows in the sand or rubble that it shares with a partner or small group, retreating to safety with remarkable speed when threatened. It tends to occur at moderate depths where current provides a steady supply of planktonic food.

The Spot-tail Dartfish is an excellent choice for peaceful community reef aquariums where a subtle, graceful mid-water presence is desired. Its calm demeanor and small size make it compatible with a wide range of tankmates, and its undemanding care requirements suit beginner aquarists. As with all dartfish species, a tightly sealed aquarium is essential to prevent jumping losses, and a sand bed of adequate depth should be provided for burrowing. The species can be kept singly or in small groups, with groups displaying more natural, confident behavior.