Five fun facts about flatfish - Oceana Canada
Home / Blog / Five fun facts about flatfish

May 27, 2021

Five fun facts about flatfish

Estimated reading time: 0 minutes


flounder or flatfish underwater in Atlantic Ocean


Make no mistake, flatfish are literally fish that are flat. And they’re pretty weird! There are many species of flatfish that call the oceans around Canada home, including American plaice, turbot, halibut and flounder. Here are five fun facts about flatfish:

1. Their eye migrates from one side of their head to the other as they grow

Amazingly, when flatfish hatch from their eggs, they resemble normal fishes. As they mature, the bones on one side of their skull grow significantly faster than on the other, so one eye and nostril slowly migrate to the other side and their body begins to flatten. By the time they reach the juvenile stage and settle on the ocean floor, they will have assumed the classic flatfish shape.

2. They are masters of camouflage 

Flatfish are truly masters of camouflage. They can mimic the ocean floor and bury themselves in the sand, only allowing their eyes – that can move independently – to be seen. Some species even have chromatophores in their skin, which are specialized cells that allow them to change colour in the blink of an eye.

3. They’re ambush predators

This is where the ability to camouflage comes in handy. Many flatfish are known to be ambush predators. This means they blend in with the ocean floor and wait. When their prey comes by, they wait for just the right moment and then attack!

4.They can be found all over the world

Surprisingly, there are over 800 known species of flatfishes all around the world! They can be found in freshwater and marine ecosystems, as well as estuaries. In Canadian waters, there are approximately 39 species of flatfishes, including American plaice and turbot.

5. The largest flatfish in the world lives in Canada

The Atlantic halibut is the largest flatfish in the world and can be found in the waters off Canada’s East Coast. They can grow to more than 2.5 metres (8.2ft) long and exceed over 300 kilograms (661lbs) in weight. Imagine seeing that in the water!

Unfortunately, only a quarter of Canada’s wild fish populations can be considered healthy. Join us by adding your voice calling on the Canadian government to make rebuilding wild fish populations a priority. You can also learn more about some of the amazing fish found in Canada’s oceans by checking out our Marine Life Encyclopedia.