Their primary habitat is coral reefs in lagoons, on reef flats and on protected seaward reefs. Juveniles associate with Acropora corals. Depth range is 3.3 – 148 feet (1 – 45 metres, perhaps up to 100 metres).
Longhorn Cowfish are yellow to tan coloured with white spots. Adults are often solitary and territorial and live around sand or rubble bottom up to a depth of 50 metres.
Longhorn Cowfish are omnivorous fish, feeding upon benthic algae, various microorganisms and foraminiferans that it strains from sediments, sponges, polychaete worms from sand flats, mollusks, small crustaceans and small fishes. The Longhorn Cowfish is able to feed on benthic invertebrates by blowing jets of water into the sandy substrate.
There is no known sexual dimorphism, so both male and female display a yellow to olive base colour, which is decorated with white or bluish spots. Paired courtship occurs just before or after sunset. Eggs and larvae are pelagic (part of the open sea or ocean that is not near the coast or sea floor).
It is apparently unique among known fish poisons; it is toxic to boxfish and resembles red tide and sea cucumber toxins in general properties.
Other unusual features: One distinction from other fish is the lack of a gill cover, which is replaced by a small slit or hole. Their unique method of swimming, called ostraciform swimming, causes them to look as if they are hovering.
