This fish has quite unjustifiably been labelled an ‘impossible’ by several writers, some of whom appear to have never even attempted to keep it. The impression that this fish is difficult to keep is undoubtedly conveyed by the enormous lengthening of the upper and lower jaw. This is an adaptation to facilitate the removal of small moluscs and crustaceans, etc. from within coral heads and would suggest that the fish is a finicky feeder. However, this fish is so tough and adaptable in captivity that it will accept all manner of the usual aquarium foods within a few days of introduction to a tank. The Yellow Longnose is at least as tough and hardy as another much maligned butterfly fish, Chelmon rostratus, but it takes to aquarium feeding much more readily than this species.

A fish of this species in good condition illustrates why the common name for the family if butterfly fishes. Most people have watched or collected butterflies when young and are familiar with the insects’ resting stance with both wings touching and in the vertical plane. The butterfly fishes are all strongly compressed laterally, and consequently in shape and often in markings, they resemble butterflies in the resting position. The slightly spasmodic movements of these fishes when searching for food among rocks and corals is also not unlike the fluttering of butterflies.