The Threadfin Cardinalfish, also known as the Longspine Cardinalfish, Bluestreak Cardinalfish or Slendertail Cardinalfish comes from the reefs of the Indo-Pacific, has a long slender shape, and is mostly transparent in color. The transparent color is offset by many markings and spots of both iridescent blue and yellow. The large black eyes of the Threadfin Cardinalfish are outlined in iridescent blue like the markings on both the fins and body.

A 30 gallon or larger aquarium with a cave and peaceful tank mates is suitable for this slow and methodical swimmer. It tends to hide in sea grass or other plants, or may use long-spined urchins for camouflage. If a larger aquarium is available, it will handle a small group of Threadfin Cardinalfish. As a group, they will establish a strict hierarchy without aggressiveness.

The Threadfin Cardinalfish requires a well balanced diet of meaty foods such as feeder shrimp, flake foods, pellet foods, marine flesh, bloodworms, and depending on its size, live feeder fish.