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Related  FAQs: Squirrelfishes 1, Squirrelfishes 2, & FAQs on: Holocentrid Identification, Holocentrid Behavior, Holocentrid Compatibility, Holocentrid Selection, Holocentrid Systems, Holocentrid Feeding, Holocentrid Disease, Holocentrid Reproduction, Pineconefishes,

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/The Conscientious Marine Aquarist

Squirrel- & Soldierfishes, Family Holocentridae, Part 1

Part 2, Part 3, Part 4

By Bob Fenner

Holocentrus adscensionis

     Do you agree that many fish family names have little to do with describing their members? A key example of family names with little useful information has got to be the "Basses" (Serranidae) of all sorts. These may be Croakers (Sciaenidae), Sunfishes (Centrarchidae), different types of 'Groupers' (Percichthyidae, et al.), etc.. And how about "Eels"? they're even worse with advanced spiny forms (Mastacembelidae), Blennies (Anarhichadidae), electrifying (Gymnotidae) Knifefish relatives, and more seemingly endless examples of relatively long 'eel-like' types.

Then there are reasonable descriptive family names like the Squirrelfishes. With their quick, jerky motions, large, bright eyes, even chattering-like noise production, these secretive fishes have much behavior in common with their terrestrial rodent namesakes.

It's a shame that Squirrelfishes are so often passed over as marine aquarium specimens. It's my guess that their bold color, frisky, but retiring conduct, and all-seeing eyes must lead aquarists to consider this group as being 'touchy' to difficult. Actually, the opposite is the case. Securing a decent specimen and granting it a few provisions will reward you with a hardy, interesting and long-term pet. Beyond that, the fact that Squirrelfishes are plentiful in the wild, easily captured, and transport well leads to their being relatively inexpensive to acquire.

Classification: Taxonomy, Relation With Other Groups

Squirrelfishes, Family Holocentridae ("Whole-oh-sen-trid-ee") are members of an Order of fishes, Beryciformes ("Bear-eh-see-form-ace"), that is not very familiar to many aquarists. This ordinal category includes the hard-to-keep Flashlight or Lanterneye Fishes (Family Anomalopidae, five genera, six species) and the bizarre deep-water Pineconefishes (Family Monocentridae). You probably know these related families from their possession of bacteria-source light organs beneath their eyes.

Monocentrus japonicus (Houttuyn 1782), the Pinconefish. To 17 cm. Indo-West Pacific; Red Sea, South Africa to Southern Japan, New Zealand. Found under ledges, in caves at depths of 20 to 200 meters (fishbase). Aquarium photo. 

Anomalops katoptron (Bleeker 1856), the western Pacific Flashlight Fish. The most common of the  six widespread species of the family Anomalopidae; mainly collected out of the Philippines (in shallow waters with cast nets). To 35 cm. Aquarium photo. 

Some fish taxonomists separate the family Holocentridae into the 'true' Squirrelfishes (Subfamily Holocentrinae) and the Soldierfishes, Subfamily Myripristinae. We won't; as they are often sold interchangeably and are approximate in their care and selection.

The Squirrelfish family Holocentridae itself is represented by about sixty five species in eight genera. If one word can describe the group, it is spiny. They have a stout pelvic fin spine with 5-8 (usually seven) soft rays, a long dorsal fin with a sharp spiny portion (10-13 spines) and soft-rayed section (11-17 rays) deeply divided by a notch; an anal fin with four spines and 7-16 soft rays. Their tail fins are sharply forked, with 18 or 19 principal rays. And their spininess doesn't end there; squirrelfishes have large, sharp, extremely rough scales. Lastly, look at the pictures presented here. What do these fishes have in common with marine angelfishes? That's right, spines on their gill covers. All these spines have functional significance; they get caught in nets and aquarists hands all too easily. More on this below.

Most Squirrelfishes are reddish in color mixed with silver and white; all have large eyes, and are nocturnal, hiding in crevices or beneath ledges by day (typically with Cardinalfishes, Bigeyes and Sweepers). These are shallow water fishes, found from the surface to about 100 meters.

In some areas of the world, the Philippines and parts of Indonesia, among others, Squirrelfishes are important as food fishes.

Natural Range  

Tropical marine, Atlantic, Indian and Pacific reefs. Tropical marine, Atlantic, Indian and Pacific reefs.


Most to about six inches in captivity, some to a foot and a half in the wild.

Species of Interest/Use to Aquarists:

The following is a (my) list of some of the more frequently offered species that are better suited for captive conditions on the basis of temperament, ultimate size and food acceptance.

Genus Holocentrus

Holocentrus adscensionis (Osbeck 1765), Squirrelfish. tropical western and eastern Atlantic. A regular offering out of the TWA, and a beautiful addition when small, but grows to about two feet if fed abundantly. This one photographed in the Bahamas. 4-40 feet.

Verticals (Full/Cover Page Sizes Available)
Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.
Holocentrus coruscus (Poey 1860), Reef Squirrelfish. Tropical western Atlantic; Florida to northern South America. A delightful offering out of the TWA. To six inches overall length. Bonaire pic taken during a night dive.

Holocentrus rufus (Walbaum 1792), Longspine Squirrelfish. Another steady catch for the pet-fish trade out of the tropical West Atlantic, at a much more manageable maximum length of fourteen inches (in the wild). Note white tips of hard dorsal fin spine membranes. Bahamas pix. 4-100 feet.

Verticals (Full/Cover Page Sizes Available
Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.


Part 2, Part 3, Part 4  

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