🐠 Squirrelfish in Punta Cana: The Big-Eyed Night Shift of the Reef

Shine a light under almost any ledge on a Punta Cana reef and there is a good chance a pair of huge dark eyes will shine back at you. They belong to squirrelfish: red, spiny, slightly startled-looking fish that spend the day parked in the shade and head out to hunt once the sun goes down. Once you know their habits, you start seeing them on every dive.

Two species share our reefs. The squirrelfish, Holocentrus adscensionis, takes its scientific name from Ascension Island in the South Atlantic, where it was first described. The longspine squirrelfish, Holocentrus rufus, is the slimmer of the pair, with a neat row of white dots along its back fin. Both are also surprisingly noisy.

Quick Facts

• Names: squirrelfish, Holocentrus adscensionis; longspine squirrelfish, Holocentrus rufus
• Size: most are 15–25 cm (6–10 in); FishBase lists a maximum of about 60 cm for the squirrelfish and 35 cm for the longspine, but fish that big are exceptional
• Diet: crabs and other small crustaceans; the longspine also takes shrimps, small snails and brittle stars
• Activity: nocturnal; shelters by day in crevices, under ledges and in the mouths of caves
• Depth: common from the shallows to about 30 m (100 ft); the squirrelfish has been recorded much deeper
• Range: western Atlantic from Bermuda and the southeastern United States through the Gulf of Mexico and the Caribbean to Brazil; the squirrelfish also lives in the tropical eastern Atlantic, from the Gulf of Guinea to Angola and around Ascension and St. Helena
• Status: both species are listed as Least Concern by the IUCN

How to Recognize a Squirrelfish

Start with the eyes. Squirrelfish have enormous eyes for their size, and they give the fish its permanently surprised look. The body is red to reddish orange, often with paler silvery stripes along the sides, and it is covered in large, rough scales. The spiny dorsal fin is tall and can be raised like a crest, and the tail is deeply forked. There is also a sharp spine at the lower corner of the gill cover. The genus name Holocentrus comes from Greek words meaning roughly "spines everywhere", and it fits.

Telling our two species apart is easy once you know where to look:

• Squirrelfish (H. adscensionis): the spiny dorsal fin is yellowish, especially toward the front, and has no white spots near the tips of the spines. The body is a little deeper.
• Longspine squirrelfish (H. rufus): a small white spot sits just behind the tip of each dorsal spine, so the fin looks edged with a row of white dots. The body is slimmer and more streamlined.

The other red, big-eyed fish you will meet under the same ledges is the blackbar soldierfish (Myripristis jacobus). It belongs to the same family but has a blunter face, no long spine on the gill cover and a clear dark bar right behind the head. A few smaller squirrelfish species also live here, such as the dusky and the reef squirrelfish. They are smaller and usually tucked deeper into the reef.

Behavior: Big Eyes and Loud Voices

By day, squirrelfish hover almost motionless in the shade, often several to one overhang, each holding its own spot near the entrance. They are not so much hiding as waiting. After dusk they leave the reef and move out over the sand and seagrass to feed, mostly on crabs and shrimps that come out at night. Those oversized eyes are an adaptation to hunting in very low light, the same reason many nocturnal reef fish are red: in deep or dark water, red looks almost black and is hard to see.

Squirrelfish are also among the most vocal fish on the reef. Paired muscles running from the skull to the first ribs, right next to the swim bladder, contract very fast and make the bladder vibrate. In studies of Holocentrus, fish defending a crevice against a neighbor grunted at it, while a larger fish or a predator nearby triggered a staccato call as the squirrelfish backed into its hole. The sounds are short and low, so your regulator usually drowns them out.

Like many reef fish, squirrelfish release their eggs into open water. The young drift as plankton for a while before settling onto a reef and taking up the shady lifestyle of the adults.

You will sometimes read that squirrelfish "keep crustacean numbers in check and protect the coral". That is overselling it. They are one of many night predators of small invertebrates, an ordinary but useful part of a healthy reef food web, and that is as far as the evidence goes.

Where to See Squirrelfish in Punta Cana

Squirrelfish are common on almost every reef dive we do. Look under ledges, into the mouths of holes and in the shadows beneath coral heads, usually between about 5 and 20 m. Cuevitas, at 10 m (33 ft), is ideal: its small caves and swim-throughs are full of shaded corners, and squirrelfish share them with spiny lobsters, cleaner shrimp and swarms of glassy sweepers. On Wreck Monica, at 15 m (50 ft), check under the plates and around the boiler. The canyons of Rock City are another good place to look, and even on our shallow beginner sites they turn up under small overhangs.

Squirrelfish do not vanish during the day; they simply stay put, which makes them easy to watch. You will find them on our species guide, together with the other reef fish our guides point out most often.

Photography Tips

• Bring light. Red is the first color to fade underwater; a torch or strobe brings it back.
• Approach slowly and at the fish's level. Crowd it and it backs into its crevice.
• Focus on the eye. With a face like that, a sharp eye makes the picture.
• Look, do not reach. Crevices that hold squirrelfish often hold moray eels too, and coral is easily damaged by hands and fins.
• Keep your fins off the bottom so you do not stir up sand in front of the ledge.

Frequently Asked Questions

Are squirrelfish dangerous?

No. They are harmless to divers and are not known to be venomous. Their fin spines and the spine on the gill cover are sharp, though, which is one more reason to watch them rather than touch them.

Why do squirrelfish have such big eyes?

Because they hunt at night. Large eyes gather as much light as possible, letting them find crabs and shrimps over dark sand after most reef fish have gone to sleep.

Do squirrelfish really make noise?

Yes. They produce grunts, knocks and staccato bursts with muscles that vibrate the swim bladder, and they use these sounds to defend their crevice and to react to predators.

Can you eat squirrelfish?

They are caught and sold in parts of the Caribbean, but they are small and spiny and not a prized food fish. On our dives they are worth much more alive.

Ready to look under a few ledges yourself? Join us for a two-tank reef dive in Punta Cana and our guides will show you where the big eyes are hiding.