Triangular rockcod facts for kids

The Triangular Rockcod (Gobionotothen acuta), also known as the Triangular Notothen, is a special type of fish. It lives in the very cold waters of the Southern Ocean. You can find this fish around places like the French Southern and Antarctic Lands, the Heard Islands, and the Kerguelen Plateau.

What's in a Name?

The scientific name for this fish is Gobionotothen acuta. Let's look at what these words mean!

• Gobius comes from a Latin word. It means 'gudgeon', which is a type of small fish.
• Acuta is also a Latin word. It means 'narrow' or 'sharp-pointed'. This part of the name describes the fish's thin snout.

The common names, Triangular Rockcod or Triangular Notothen, are much easier to understand! They refer to the unique triangular shape of the first dorsal fin on its back. This fin looks like a triangle because its first spine is much longer than the others. The rest of the spines get shorter and shorter, making a sharp point. This triangular fin shape is quite rare among fish in the notothen family.

Discovering the Triangular Rockcod

This fish is a small to medium-sized notothen. Its special triangular first dorsal fin helps scientists tell it apart from other similar fish. The first spine in this fin is longer than the rest. The other 5 to 6 spines then get shorter, making a clear triangle shape.

Body Features

The fish has short, blunt gill rakers. These are small parts in its gills that help it filter food. Its pectoral fins have irregular stripes. They reach back to above the 7th to 9th rays of its anal fin. The pelvic fins do not reach the start of the anal fin. The caudal fin, or tail fin, is slightly rounded. It has faint stripes and 10 branched rays.

Colors and Patterns

The body of the Triangular Rockcod often looks marbled. It has three or four short, wide, dark bars on its upper sides. There are also different dark blotches that are not in a regular pattern. Sometimes, you can see small, dark spots on the rays of its dorsal fin. The top and sides of its head are dark, with dark spots too. A dark area in the middle and a horizontal line are on its upper lip. This line continues onto its lower lip and part of its lower jaw. The longest Triangular Rockcod ever recorded was about 35 centimeters (13.8 inches) long.

Life in the Ocean

The Triangular Rockcod is a benthic species. This means it lives on or near the bottom of the ocean. It prefers fairly shallow waters, usually from 30 meters (98 feet) deep down to about 140 meters (459 feet). Sometimes, it can be found as deep as 300 meters (984 feet), but this is not common.

What It Eats

This fish is a predator. It hunts and eats small creatures that live on the ocean floor. Its main food sources are amphipods and isopods. It also eats polychaetes, which are a type of worm, and sometimes even tiny phytoplankton.

Who Eats It?

The Triangular Rockcod is also food for other animals. In the Kerguelen Islands, gentoo penguins and Antarctic fur seals hunt this fish. The black-browed albatross is also known to eat the Triangular Rockcod.

Reproduction and Life Cycle

Female Triangular Rockcod can lay a lot of eggs! In the Kerguelen Islands, one female can lay anywhere from 41,650 to 86,580 eggs. The very first specimen of this fish that scientists studied was collected from the Kerguelen Islands in May 1879.

Commercial Use

This fish is not very important for commercial fishing. In 2010, only about 2 tons (2.2 tonnes) of Triangular Rockcod were caught.