Ocean Sunfish

Details

The ocean sunfish (Mola mola) is among the heaviest bony fishes (family Molidae). It has a huge disc‑shaped body, the caudal fin reduced to a clavus, and frequently basks at the surface. Diet is dominated by gelatinous zooplankton (jellies, salps, ctenophores) with supplements of small fishes, cephalopods and crustaceans. IUCN: Vulnerable (VU).

Ecology & Behaviour

• Extraordinary fecundity: females release hundreds of millions of eggs; eggs/larvae pelagic.

• Diel vertical migration: deep daytime foraging and surface basking for re‑warming; linked to thermoclines/fronts.

• Cleaning associations: visits reef cleaning stations; seabirds also remove parasites at the surface.

Identification

Round/oval disc with no true tail; tall, symmetric dorsal/anal fins; rough denticulate skin; small mouth with fused plates. Often confused with Mola alexandrini, separable by head profile and clavus morphology.

Size & Longevity

• Length: commonly 1.8–2.3 m disc; max ~3.3 m.

• Mass: typically 250–1,000 kg; records >2,000 kg.

• Life: 20–30+ yrs wild; longer in captivity.

Range & Habitat

Nearly worldwide in temperate–tropical seas over the outer shelf and slope; from the surface to mid‑waters (~0–800 m).

Threats & Conservation

• Bycatch in drifting gillnets, longlines and purse seines.

• Marine debris ingestion/entanglement.

• Vessel strikes & noise due to near‑surface behaviour.

• Taxonomic confusion with congeners.

Priorities: bycatch reduction, speed limits/buffer zones in hotspots, better ID/monitoring and plastic‑waste control.