Caribbean Longnose Butterflyfish

Caribbean Longnose Butterflyfish

The Caribbean Longnose Butterflyfish (Prognathodes aculeatus), also called the longsnout butterflyfish, is a small, refined Atlantic species with a yellow-and-white body and a distinctive elongated snout. That probing mouth is a tool: it lets the fish reach into cracks and crevices to extract small invertebrates, giving it a delicate, deliberate feeding style. It is a charming, peaceful fish for the experienced marine keeper who can satisfy its diet.

Less destructive than some butterflyfish, it nonetheless calls for caution in a reef with prized invertebrates.

Natural Habitat & Origin

Prognathodes aculeatus is found in the Caribbean and western Atlantic, often on deeper reef slopes and around rubble and rock, where it probes crevices for small invertebrates. It is frequently seen alone or in pairs, working methodically over the reef.

In the aquarium it appreciates plenty of live rock with crevices to forage in, in a mature system rich in microfauna, and calm tankmates.

Care Requirements

Maintain stable marine conditions: salinity around 1.024–1.026, pH 8.1–8.4, and a temperature of about 24–26°C (75–79°F). Reaching only about 10 cm (4 inches), it suits a tank of around 200 litres (about 55 US gallons) or more with ample rockwork. A mature system with natural microfauna is a real advantage, and subdued lighting can help a deeper-water fish settle.

Diet & Feeding

This butterflyfish is a carnivore that picks small invertebrates — worms, tiny crustaceans and similar — from the reef. It can be a particular feeder at first: tempt it with frozen mysis and enriched brine shrimp, finely chopped seafood and small marine preparations, fed in frequent small amounts. A tank with established microfauna helps support it as it transitions to prepared foods.

Behavior & Temperament

It is a peaceful, somewhat shy fish that mixes well in a calm community and can be kept singly or as a pair. It rarely troubles other fish and spends its time methodically foraging over the rockwork. Avoid aggressive or fast tankmates that will outcompete it for food.

Tank Mates

Good companions are other peaceful marine fish — anthias, peaceful wrasses, gobies, cardinalfish and similar. In a reef it should be treated with caution: while it favours small invertebrates over coral, it may sample ornamental invertebrates or coral polyps, so it is safest in fish-only systems or reefs without prized small invertebrates.

Breeding

Prognathodes aculeatus is a pelagic spawner with planktonic larvae and is not bred in the home aquarium. Trade specimens are wild-collected.

Common Health Issues

The main challenge with this species is establishing it on prepared foods; a thin, non-feeding specimen needs frequent tempting with live or rich frozen foods. Like all marine fish it is also susceptible to marine ich (Cryptocaryon irritans) and marine velvet (Amyloodinium ocellatum), particularly when stressed. Quarantine new arrivals, keep water quality stable, and choose a feeding specimen. Given a mature tank and a varied diet, it is an elegant and rewarding butterflyfish for a patient, experienced keeper.