O-Fish-ial Fun Fact Thursday — 16 April 2020

Hello, and welcome to O-Fish-ial Fun Fact Thursday. This month, we’re looking at fish that are named after other animals.

Today we’ll be looking at the Longhorn Cowfish, or for fancy people, Lactoria cornuta.

I’m cute and pretty

How big does it get?

The longhorn cowfish can get to 50cm long. They live for up to 8 years.

Where can I find it?

The Indian and Pacific oceans, on coral reefs that are protected from heavy currents and surges, typically from 1 to 50 metres in depth.

What does it eat?

Small bottom-dwelling invertebrates.

What makes it interesting?

• It is also known as the horned boxfish. Those horns are what give it the “cow” in cowfish.
• The adult fish are shy, solitary and territorial, while the juveniles form small schools. (In my head, I can just imagine an adult cowfish yelling at a school of juvenile cowfish to get off his lawn).

Hey, you kids! Get off my lawn!!

• They appear to hover in the water column. They do this by performing something called ostraciiform swimming. By moving the pectoral and dorsal fins, they are able to maintain their position in the water column.
• They are poisonous. They excrete a toxic mucous from their skin when stressed, called pahutoxin or ostracitoxin. It is a toxin which affects other fish by destroying the red blood cells. It is not harmful to humans. It is released when the fish becomes stressed by sudden movements, bright lights or loud sounds.
• They have been associated with incidents of ciguatera fish poisonings. Essentially this is caused by eating the fish, and is unrelated to the ostracitoxin. The poisoning is actually caused by a dinoflagellate which is a kind of algae.
• Those horns are thought to have evolved to deter predators. It makes the cowfish more difficult to swallow.
• The horns can and do snap off occasionally. They do grow back in a few months.
• They feed on small invertebrates that are found in the sand. They blow water into the sand which dislodges the invertebrate. The cowfish then snaps the invertebrate up.
• They are very fond of sunsets. Courtship and mating only happens just before or just after sunset.

And long walks on the beach! And puppies!

• They are used in the aquarium trade, although they are not suited for home aquariums. With their ostracitoxin, a sudden movement or a sudden change in light will cause them to release this toxin into the water, and will result in all the other fish in the aquarium getting poisoned.