Splendid Toadfish in Cozumel

A small, flat-headed fish with a maze of pale lines across the head, a dark body and a bright yellow margin running along every fin. Nothing else on a Cozumel reef looks like it. It is not scarce — it is cryptic, wedged under coral overhangs and almost entirely hidden by day, which is a different problem.

Quick ID

Why It Only Lives Here

The splendid toadfish was described in 1974 from Cozumel and for years was treated as endemic to the island. Records since then extend it to reefs off Belize, and divers report it along the Yucatán coast, so "endemic" is not quite exact. What is exact: Cozumel is the only place in the world where it is common and reliably seen. That is why it appears on almost every dive-shop logo on the island.

Where You Will See It In Cozumel

Shallow and mid-depth reefs with cut coral heads and sand chutes — the shelf reefs rather than the deep walls. Look at the base of a coral head where it meets sand, in the shaded gap underneath.

Reliable sites: Paradise Reef, Chankanaab Reef, Yucab, Tormentos, Paso del Cedral.

How To Actually Find One

The fish does not move, so searching for movement fails. Look for the den instead: a small sloping fan of clean sand at the mouth of a gap under a coral head, pushed out by the fish. Then look into the shadow above it. Most divers swim past at exactly the depth the fish lives at without ever looking under anything.

A guide who knows a specific den will find one in seconds. A diver hunting blind may go a whole week without seeing one.

Behaviour

An ambush predator that sits in the mouth of its den and takes small fish, snails and polychaete worms that come past. It is nocturnal, so daytime sightings are of a fish sitting still and waiting for dark.

Toadfishes make sound with muscles against the swim bladder, and this one is no exception — a low grunting buzz, loudest around breeding. Divers occasionally hear it before they see it.

Commonly Confused With

• Spotted scorpionfish — Also flat and tucked under structure, but mottled brown and grey with no yellow fin edges and no line pattern on the head. See spotted scorpionfish.
• Whitespotted toadfish (Sanopus astrifer) — Same shape and habit, but covered in white spots. It lives off Belize, not Cozumel.
• Moray eel in a hole — At a glance, any dark shape under a ledge reads as a moray. The toadfish has a broad flat head and fins; a moray has neither.

Diving Etiquette And Safety

Not venomous, and not aggressive. It does have strong jaws, and every reason to be left alone.

It is Endangered and it lives inside a national park. Do not touch it, do not move coral or rubble to see it better, and do not chase it out of its den for a photograph — a fish forced out of cover in daylight is exposed to predators. Shoot from outside the overhang, angle a strobe in rather than pushing a lens in, and keep fins off the reef.

Part of the Cozumel marine life guide · see Cozumel dive sites · plan your Cozumel dive trip

Photo: Pauline Walsh Jacobson, CC BY 4.0, via Wikimedia Commons. Size, depth and conservation data from FishBase and the IUCN Red List assessment of 21 August 2012.