Information on the Longnose Butterfly Fish

The longnose butterfly fish is a popular addition to many tropical saltwater aquariums. The name often applies to two species of butterfly fish, Forcipiger flavissimus and Forcipeger longirostris, with the primary difference between the two being the length of their snouts. The Hawaiians gave the same name to both fish, lau-wiliwili-nukunuku-'oi'oi, which refers to their long nose and yellow color. Because the name longnose applies to both fish, the more common species, Forcipiger flavissimus, is the forceps butterfly fish or the yellow longnose butterfly fish, while its less common relative Forcipiger longirostris is the big longnose butterfly fish.

  1. Characteristics

    • Both species of butterfly fish possess a long snout. Their flat yellow bodies resemble yellow leaves (hence, the Hawaiian reference of wiliwili, a tree with yellow leaves). Their head regions are white on the bottom half and blue to black on the upper half. A black, false eye spot is near the tail. These fish can reach up to 4 inches in length.

    Habitat and Distribution

    • Longnose butterfly fish live in shallow regions along coral reefs from Northwest Australia across the Pacific to the Hawaiian Islands. The forceps butterfly fish is extremely common in most of these areas, while the big longnose, while relatively common, is encountered less frequently and typically swims in deeper areas around coral reefs.

    Diet

    • The longnose butterfly fish feed on small invertebrates and pieces of prey by foraging in the nooks and crannies of the coral reef. F. longirostris engulfs prey whole, while the jaws of F. flavissimus allow it to bite pieces of food from larger prey such as the tube feet of sea urchins.

    Related Fish

    • You can distinguish the longnose butterfly from most other butterfly fish by its long snout. Although the big longnose butterfly fish (Forcipeger longirostris) appears similar, the F. flavissimus has a shorter snout, slightly fewer dorsal spines (10 to 11 versus the 12 to 13 found on the big longnose) and small black spots on the breast.

    Aquarium Care

    • Longnose butterfly fish prefer a mixture of habitat with hiding spaces accompanied by some areas for open swimming. For this reason, longnose are typically in medium-sized (40 gallon) or larger aquariums with a temperature between 72 and 78 degrees. These fish are not normally anti-social but are sensitive to the predation and aggressive behaviors of other tank inhabitants. They feed on a meat diet, and will take dry, frozen, or fresh crustaceans, mollusks and worms.