Adult Long Horn Cowfish

The longhorn cowfish, Lactoria cornuta, is a boxfish with a rigid body and conspicuous horns. Its unusual shape comes with unusual care needs: this is a specialist fish for a spacious, established marine aquarium with broad swimming routes and shelter that will not trap or scrape its body. Reported adult length can reach about 50 cm (20 inches), making long-term swimming and turning space essential.

Offer varied marine meaty foods alongside vegetable and algae-based foods. Cowfish feed slowly, so watch that faster tankmates do not take the entire meal. Rock surfaces provide grazing opportunities, but natural growth is only part of its feeding plan.

Compatibility needs particular care because a severely stressed cowfish can release toxins that endanger other aquarium inhabitants. Avoid aggressive fish and other longhorn cowfish, and assess the risks before placing it with valuable reef livestock. Tubeworms and other invertebrates may be nibbled.