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/A Diversity of Aquatic Life

My What Big Eyes You Have, Family Priacanthidae

Bob Fenner

  Priacanthus cruentatus

The Bigeyes or Catalufas are some of the oddest looking fishes in the seas, with their gigantic eyes, oblique landing-craft jaws, stationary orientation, brilliant red colorations; but all this shouldn't be cause for you to summarily dismiss them as aquarium choices.

Appearances can indeed be deceiving; this family's members are undemanding and tough, adding a splash of color and reflection along with their comical looks. Outside of general marine system considerations, all the Bigeyes require is a nice dark area to get away, training to non-live food, and extra care in moving.

Classification: Taxonomy, Relation With Other Groups

The family of Priacanthids is all marine, and although not big (four genera with about 18 species) has a widespread range; Atlantic, Indian and Pacific oceans, tropical and subtropical. On both coasts of the U.S. big eyes occasionally are found way up north, delivered by warming currents.

What do they look like to you? Dear Reader I must admit to finding several Bigeye slides misidentified in my files as Squirrelfishes! Now, be honest with me, wouldn't you make this mistake too? But the squirrels (family Holocentridae) are not very closely related. Bigeyes dorsal fins are not strongly notched like theirs, and squirrels have small non-oblique mouths. A sure-fire difference between the two is the Bigeyes pelvic fin membranes that attach from between the spines to the body.

The circumtropical Glasseye, Heteropriacanthus cruentatus (Lacepede 1801), can be found most anywhere seawater is warm on the planet. It grows to a maximum of one foot in length. One in St. Lucia in the Caribbean, another in the Galapagos.

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My favorite of the family is the handsomely red, Crescent-Tail Bigeye, Priacanthus hamrur (Forsskal 1775), widely taken in the Pacific to the Indian Ocean and Red Sea. Be aware that this fish can get to eighteen inches long; feed sparingly. Red Sea image.

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Genus Pristigenys:

Of species occasionally available, the Short Bigeye, Pristigenys alta (Gill 1862), makes its way up to Jersey shores and can be hand-net collected there or purchased from Caribbean points southward. Tropical west Atlantic. To a foot in length. 100-660 feet

The striped Japanese Bigeye, Pristigenys niphonia is offered from time to time from the Indo-Pacific, as is the Popeye Catalufa, Pristigenys serrula (Gilbert 1891), from the eastern Pacific, generally from Mexico. The latter pictured here in an aquarium.

Pristigenys serrula (Gilbert 1891), the Popeye Catalufa. Eastern Pacific; Monterey to Peru. To thirteen inches in length. Nocturnal, hides during the day as the Cardinalfishes, Squirrelfishes. This one at the Birch Aquarium, UCSD, San Diego. 

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Most to about a foot in captivity; sometimes quickly with substantial feeding.


Sorting through Bigeyes is pretty straightforward; they only come in two "grades"; super-duper and soon-to-be-dead. Distinguishing betwixt the two is done on two bases, both observational. Number one, look for evidence of health; clear, clean eyes, lack of apparent thrashing by netting, or shipping. Secondly, ask for the specimens to be fed in your presence; it/they should.

Remember the old paper-grading slogan, "when in doubt, count it out"; and come back some other time if you have lingering concerns.

When you're moving these fishes, bear their large, bulbous eyes, large, spiny fins, and rough scales in mind. They should never be raised into the air with a net, but instead guided into a submerged double-bag to avoid damage.

Environmental Conditions:

Priacanthids have only one special habitat need; a dark space to call their own. They are singularly lethargic, moving only slightly and slowly, but have to have a low lit place. Bigeyes have a peculiar reflective layer at the back of their eyes, the tapetum lucidum, that allows for clear vision in low light conditions; at night time when they go in slow search of food. One common name for the group, the Glasseyes, refers to this brilliant "eyeshine".

Display ideally includes a large rear wall rockwork with at least a single opening for your Bigeye to call its own; and a subdued lighting regimen.



Though not territorial per se, most of the Bigeyes are solitary by nature, and do fine kept one to a tank.


Is simple as a standard quarantine, and/or dip/bath, and placement in the main-display system. These fishes are celebrated as being hardy and non-disease transmitters.

Predator/Prey Relations

For the most part nothing fools with a Bigeye; maybe it's their bright red warning color, perhaps their spininess...? I've eaten their flesh, and can tell you they are tasty, so it's not that their unpalatable.


Very little. Part of the charm/allure of Bigeyes is their all seeing eyes and immobile watching of their world. They can remain undetectably motionless for hours.

Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes

Bigeyes are nocturnal and carnivorous; in captivity they can usually be trained to accept non-live food. This is generally best offered near "nighttime" or when you're turning off the lights for the day. Brine shrimp and small worms, freshwater, marine or terrestrial are fine for smaller specimens... larger ones may require coaxing with ghost shrimp, feeder fishes of various sorts.


What's that red fish with the big eyes? Is it a Squirrelfish, a big Cardinal? Don't be so sure. Looking for a bit of color in a sedentary animal? Perhaps something seemingly clairvoyant? A Bigeye could be for you. You will have to train it to take non-live foods or provide live; and provide a nice, dark cave. But that's about it.

Bibliography/Further Reading:

Burgess, Warren E. 1978. The genus Pristigenys. TFH 7/78.

Nelson, Joseph S., 1994. Fishes of the World, 3d ed.. Wiley & Sons, NY.

Quinn, John R., 1988. The eyes have it. TFH 8/88.

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