Sunfish
Sunfish are a group of fish best known for the ocean sunfish, or mola, which is the heaviest bony fish.
Sunfish are a group of fish best known for the ocean sunfish, or mola, which is the heaviest bony fish. The term also refers to freshwater sunfishes in the family Centrarchidae, including species common in Canada and the United States. Because the user’s topic is broad, this page focuses on the ocean sunfish as the best-known meaning while noting the freshwater group where relevant.
Classification and naming
The name sunfish can refer to two different fish groups: the ocean sunfishes in the family Molidae and the freshwater sunfishes in the family Centrarchidae. In general usage, however, sunfish often means the ocean sunfish, Mola mola.
Appearance and size
Ocean sunfish are famous for their unusual, flattened shape and very large size. They can grow to about 4 metres long and weigh up to roughly 2.5 tonnes, making them the heaviest bony fish, surpassing even the Sturgeon in weight.
Diet and behaviour
Ocean sunfish feed mainly on jellyfish and other soft-bodied prey, but also eat small fish, squid, crustaceans, and gelatinous zooplankton. They are open-ocean fish and may move through different depths during the day.
Distribution and habitat
Ocean sunfish occur in tropical and temperate waters around the world, while freshwater sunfishes live mainly in North American lakes, rivers, and ponds. Their habitat depends on which meaning of sunfish is intended. Freshwater sunfishes are part of the diverse fish fauna of North America, which includes Walleye and Tilapia.
Human interactions
Sunfish are not considered dangerous to humans and are often described as harmless. Ocean sunfish are more threatened by fishing gear, boat strikes, and other human impacts than they are a threat to people.
Key facts
- Ocean sunfish are among the largest bony fish in the world.
- They feed mainly on jellyfish and other gelatinous animals, but also take other small prey.
- Freshwater sunfishes in the family Centrarchidae are widespread in rivers, lakes, and ponds in Canada and the United States.
- Sunfish are generally harmless to humans, though large individuals can injure people accidentally if handled or approached closely.
- Ocean sunfish are vulnerable to bycatch and collisions with boats.
Freshwater sunfishes are common in Canada’s lakes, rivers, and ponds, and the ocean sunfish is occasionally relevant to Canadian waters through Atlantic and Pacific marine ecosystems.
Frequently asked questions
What is a sunfish?
How big do sunfish get?
What do sunfish eat?
Where do sunfish live?
Are sunfish dangerous?
References
- U.S. National Park Service — https://www.nps.gov/amis/learn/nature/sunfish.htmSupports: Freshwater sunfishes are widespread across the continental United States and Canada; they occur in rivers, lakes, and ponds.
- National Geographic Kids — https://kids.nationalgeographic.com/animals/fish/facts/molaSupports: Ocean sunfish size, global tropical and temperate ocean range, and harmlessness to humans.
- Smithsonian Ocean — https://www.smithsonianmag.com/science-nature/mola-mola-oceans-gentle-giant-180952971/Supports: Ocean sunfish diet, open-ocean habitat, and lack of danger to humans.
- Animal Diversity Web — https://www.animaldiversity.org/accounts/Mola_mola/Supports: Ocean sunfish distribution in tropical and temperate oceans and diet including jellyfish and gelatinous zooplankton.
- Hebridean Whale & Dolphin Trust — https://www.hwdt.org/sunfishSupports: Ocean sunfish range, diet, and notes on bycatch and boat collisions.