The Indo-Pacific cowfish is the species Lactoria cornuta, commonly called Longhorned cowfish. By far, this is the most well-known cowfish species in the aquarium trade. There is no known sexual dimorphism, so both male and female display a yellow to olive base color, which is decorated with white or bluish spots. A pair of horns protrude above each eye and from each side of the back ventral region. The long horns that this species is named for, grow proportionally smaller to the body as the fish age. They are one of the largest cowfish known. In the wild, Longhorn cowfish are often found solitary in sand or rubble bottoms of lagoons up to 50m in depth. They range from the Red Sea to Marquesas and Tuam Islands, including Korea, Japan, and Lord Howe Islands.They can grow up to 18 inches in the wild, but seldom reach more than 12 inches in captivity. Even so, they require an extremely large aquarium of 135 to 180 gallons.
They are able to feed on benthic invertebrates by blowing jets of water into the sandy substrate. Their diet includes polychaete worms, but they will consume other small invertebrates in the sand as well. They should be fed a variety of foods, including fish, clams, squid, octopus, shrimp, etc. They also require an equal amount of plant foods, such as seaweed and spirulina. Occasional offerings of pre-frozen peas and corn are also acceptable. In captivity, they equate the water's surface with feeding and will blow water out of the tank when they want food. It is one of the more entertaining boxfish species, as it will spit water from the tank or flap its pectoral fins at the waters surface to get attention.
By no means should this fish be fed floating foods. Longhorn cowfish are susceptible to buoyancy problems when they ingest air from the water's surface. Buoyancy disorders are nearly impossible to cure. Optimally, they should be fed three small meals per day. Live rock is a good supplemental food source for Longhorns, but they are not reef compatible as they naturally consume small invertebrates.
As the fish ages, its color fades slightly, and the horns become proportionally shorter. This fish will do best kept as a single specimen or with non related species of peaceful nature.
Larger individuals are more sensitive to quick light changes. Be sure to turn lights on and off in increments so that the fish doesn't panic and crash into tank walls or try to jump out of the tank. If severely stressed, this species can exude deadly toxin. Although toxin release is not common, its ill effects can be reduced if carbon is run in the tank or filtration system. Any sick or injured cowfish that appear to be dying shoud be removed from the main aquarium so that they do not poison the tank in their final moments of life.
