Longhorn Cowfish

Looks how to spot one

Boxfish with a rigid carapace and two long horns

The body is a hard box made of fused six-sided bony plates, with two long horns pointing forward above the eyes. It is yellow to olive with white or bluish spots. The horns are mostly hollow and can grow back if damaged.21

Personality what they are like

Generally peaceful but can be territorial toward other cowfish or similar boxfish. Adults are shy in the wild.312

Daily activity how busy a day looks

A slow swimmer that moves mainly by its fins and tail tip. It prefers gentle water flow.23

Grooming and care the hands-on bits

Rated expert-only care. Not reef-safe, as it may nip corals and small invertebrates. It is a slow eater, so avoid fast, pushy tankmates that would out-compete it at feeding time.3

Home where they are happiest

A very large tank of at least 180 US gallons (about 680 L) for one fish, with low flow. Saltwater at 22 to 26 °C (72 to 78 °F), pH 8.1 to 8.4, specific gravity 1.020 to 1.025. Wild adults live over sand and mud in sheltered bays, harbours and estuaries at about 1 to 50 m, and young fish use shallow brackish flats.31

Food basics what goes in the bowl

An omnivore. Offer meaty foods such as shrimp, clams, mussels and bloodworms, plus algae-based foods. Wild fish blow jets of water into the sand to uncover small invertebrates.321

Company who they like around

Adults live alone, while juveniles gather in small groups. In aquariums keep one per tank.13

The story where it all began

Carl Linnaeus described the species in 1758 as Ostracion cornutus. The genus name Lactoria means milk cow, a nod to its cow-like horns, and cornutus means horned. It is the best-known cowfish in the aquarium hobby.2

Recognised by the official bits

IUCN Red List

Least Concern (assessed 2023)1