Giant sunfish
The heaviest bony fish in the world, found in warm oceans.
The giant sunfish (Mola alexandrini) is a large ray-finned fish belonging to the family Molidae. It holds the record for maximum weight among bony fishes, reaching over two tonnes. This species inhabits tropical and temperate seas across the Southern Hemisphere.
- Heaviest bony fish recorded at 2,744 kg
- Lacks tail fin, ribs, and pelvic fins
- Dives deep to cool muscles and recharge oxygen
- Eats jellyfish, plankton, and small crustaceans
- Spawns in open oceans and Mediterranean Sea
What it is
The giant sunfish is a massive ray-finned fish known for its extreme weight. It possesses a flat, round body covered in rough, leathery skin with brown and gray coloring. A thick gelatinous layer lies beneath the surface. The fish lacks a tail fin, ribs, or pelvic fins, relying instead on dorsal and anal fins for movement. Its mouth features fused teeth forming a beak-like structure. Adults can grow up to 3.3 metres long. The heaviest recorded specimen weighed 2,744 kilograms, caught off Portugal in 2021.
Where it lives
This species lives in oceans worldwide, avoiding polar areas. Sightings occur near Japan, Taiwan, New Zealand, Australia, Chile, South Africa, Turkey, Oman, and Spain. In the southwest Pacific, they are common around Australia and New Zealand. Seasonal migrations happen in Japanese waters, moving north in summer and south in winter. These movements follow temperature changes and productive ocean fronts. They generally inhabit the epipelagic zone but also venture into deeper waters.
How it lives
Sunfish swim by oscillating their dorsal and anal fins simultaneously. They often dive below the thermocline during the day to cooler depths and rise to warmer surface waters at night. This vertical movement helps regulate body temperature and replenish oxygen stores. They hunt in dynamic frontal systems, consuming abundant but low-nutrient prey like jellyfish. Predators include tiger sharks and orcas, though attacks are rare due to the fish's tough dermis.
Breeding and life cycle
Reproduction occurs in the outer circulation of major oceans and the Mediterranean Sea. Females release up to 300 million eggs into the water for external fertilization. Larvae hatch at roughly 1.4 millimetres and grow through juvenile stages. As they mature, distinct physical features develop, including head bumps and chin bumps. Spawning in autumn or winter may result in larger offspring, though optimal wild timing remains unclear.
Fish and people
These fish attract tourism interest, particularly in Bali, the Galapagos Islands, and the Mediterranean. Scuba diving tours frequently target them. Commercial fisheries in Taiwan and Japan occasionally catch them. In Indonesia, they are sometimes eaten locally or used as bait. Conservation status is not formally evaluated by the IUCN, but they face risks from bycatch in longline fisheries globally. Some governments have begun listing them for protection.
Status and threats
The International Union for Conservation of Nature has not assessed this specific species. However, related sunfish face high bycatch rates in South African and Australian fisheries. They are considered high-risk bycatch in eastern Australian longlines. Threats include accidental capture in commercial fishing operations. Indonesian authorities have included them in protection plans. Their role in marine food webs remains poorly understood despite their size.
Questions people ask about Giant sunfish
How heavy can a giant sunfish get?
The heaviest recorded specimen weighed 2,744 kilograms. This individual was caught off the coast of Faial Island in Portugal in late 2021. It exceeds the previous record holder by nearly half a tonne.
What does the giant sunfish eat?
They primarily consume jellyfish, which are abundant but low in nutrition. Their diet also includes brittle stars, plankton, algae, salps, mollusks, ctenophores, hydrozoans, and small crustaceans. Juveniles feed in coastal areas while adults dive deeper.
Where do giant sunfish live?
They are found in tropical and temperate oceans worldwide, excluding polar regions. Common locations include waters off Japan, New Zealand, Australia, Chile, South Africa, and the Mediterranean Sea. They prefer temperatures between 16.8 C and 25.6 C.
Are giant sunfish dangerous to humans?
No, they are not dangerous to humans. They are gentle giants that pose no threat to swimmers or divers. However, they face threats from predators like tiger sharks and orcas, although such attacks are rare.
Good reading and sources
The facts on this page come from the Wikipedia article "Giant sunfish", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.
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