The ocean sunfish looks like a giant swimming head and is often seen lying flat at the surface. That lazy look is misleading: it is a deep diver that comes up to warm itself between hunts.
A tall, flat, oval body about as deep as it is long, with no real tail: the very tall dorsal and anal fins sit at the back and join a short rudder called the clavus, whose edge is wavy and carries 8 or 9 small, widely spaced bony plates. Tiny beak-like mouth, small rounded pectoral fins, thick sandpaper skin. Gray-brown to dark blue above, often with pale blotches, silvery below.
The ocean sunfish lives in tropical and warm-temperate seas around the world, and the Smithsonian’s guide to eastern Pacific fishes records it off Baja and in the Gulf of California. In the first long-term tagging study in the eastern Pacific, 15 sunfish tagged off southern California spent the fall and winter moving down to northern and central Baja; the largest, about 2 m long, travelled more than 800 km to Punta Abreojos, Baja California Sur. By day they spent most of their time below 50 m, by night almost all of it in the top 50 m, with occasional dives past 500 m into water as cold as 6.6 °C.
Sunfish carry an unusual load of hitchhikers: some 40 genera of parasites have been recorded on this species, from copepods on the eyes to larval shark tapeworms. Small fish and birds pick them clean, from gulls in California kelp beds to the open ocean, where albatrosses in the North Pacific and giant petrels in the South Atlantic have been photographed cleaning them. Sea lions and orcas prey on them, and off California they make up the largest share of the bycatch in the drift gillnet fishery.
The 2,300 kg fish caught off Japan in 1996, long quoted as the heaviest ocean sunfish, was actually a giant sunfish, Mola alexandrini. Of 15 molids reported at over 2,000 kg, researchers identified 14 as M. alexandrini and only one as M. mola; just five had really been weighed.
Source ↗The famous figure comes from a single sentence in Nature in 1921: about 300 million unripe eggs in the ovary of one female around 1.4–1.5 m long. No method, ovary weight or sample count was given, the fish’s species is uncertain, and in over a century no one has repeated the count.
Source ↗Camera and accelerometer tags on sunfish off Japan showed them diving to 100–200 m by day to eat siphonophores in water below 12 °C. Their body cooled at depth, and at the surface they took up heat 3 to 7 times faster than they lost it, so basking lets them stay longer in cold hunting grounds.
Source ↗DNA from the stomachs of 57 sunfish in the northeast Atlantic revealed 41 prey types, and jellies and their relatives made up only 16% of what they ate. Smaller sunfish fed mostly on small crustaceans and fish; bigger ones ate more jellies.
Source ↗Between 2013 and 2024, researchers documented 21 orca attacks on sunfish in the southwestern Gulf of California, involving three sunfish species. The sharptail mola made up 66% of confirmed records, and calves were present in 8 attacks, suggesting mothers use sunfish to train their young.
Source ↗A sunfish that arrived at the Monterey Bay Aquarium in 1997 weighing 57 lb (26 kg) reached 880 lb (about 400 kg) in 14 months, roughly 1.1 kg a day. It had to be lifted out by helicopter and released at sea before it grew too big to move.
Source ↗Ocean sunfish are an occasional surprise off Los Cabos rather than something you can plan a trip around. Local reports include a sunfish of about 450 lb that a Cabo crew fought for two hours on 50 lb tackle in June 2008, a video of divers swimming with one off Cabo San Lucas that went viral in 2025, and a December 2025 sighting in Bahía Magdalena that the diver who filmed it described as rare for Baja California Sur. Sunfish photos are seldom checked by specialists, and around the southern Gulf the sharptail mola and the giant sunfish also turn up.
If you spot one basking on a trip offshore, slow down, keep some distance and let it be; it may be warming up after a deep dive. Sunfish aren’t a sport fish, so if one takes a bait, cut the line as close as you safely can and release it in the water rather than lifting or gaffing it.
| Mexico (NOM-059) | Not listed |
|---|---|
| Sport fishing | Not a sport species; not among the species reserved for sport fishing in Mexico |
| IUCN Red List | Vulnerable (2015) |
| CITES | Not listed |
Many sunfish sightings are never identified to species. In a recent study of orca attacks in the southern Gulf of California, the sharptail mola made up most of the confirmed records.
The sharptail mola (Masturus lanceolatus) has a rudder with a pointed central extension and is the sunfish most often confirmed in the southern Gulf. The giant sunfish (Mola alexandrini), first reported there in 2022, has bumps on the forehead and chin and a rounded rudder edge without the wavy outline. The hoodwinker sunfish (Mola tecta) has never been reported in the Gulf of California.
Occasionally. Local reports describe scattered sightings by divers and fishing crews, mostly in the cooler months, but it’s rare and never guaranteed.
Not quite. The heaviest bony fish ever weighed was a giant sunfish, Mola alexandrini: 2,744 kg, found in the Azores in 2021. Ocean sunfish over 2,000 kg are very rarely confirmed.
That number comes from a single 1921 count of unripe eggs in one female, with no method described. It may be right in order of magnitude, but it has never been verified.
Top illustration: Top Anglers. Photos: iNaturalist contributors, credited on each photo.
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