Ask the WWM Crew
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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.
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.
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.
Selecting Healthy Specimens
In terms of picking out a healthy specimen, be wary of any squirrelfish in a group with others that display: 1) reddening in patches, especially around fins and under the body. This is often a sign of rough handling and bacterial (Aeromonas, Vibrio) infection; usually fatal. 2) Torn fins, cheekspines, scales, see 1), and/or 3) evidence of external parasite/removal damage.
Collecting Your Own
Compared to other marines is a breeze. Squirrelfishes are easily spooked out of hiding into a carefully placed barrier or mist net and hand netted from there. Care must be taken to not damage the catch by tangling and pulling on it in the netting; or the captor by getting poked but good by the squirrelfish's spines and sharp scales. compared to other marines is a breeze. Squirrelfishes are easily spooked out of hiding into a carefully placed barrier or mist net and hand netted from there. Care must be taken to not damage the catch by tangling and pulling on it in the netting; or the captor by getting poked but good by the squirrelfish's spines and sharp scales.
Can you replicate the hiding netherworld of ledges and coves by day, the bottom, food searching, nocturnal swimming space by night?
Not demanding; lower temperatures are preferred, 72-78 degrees F.. Higher temperatures may bring on a feeding strike and odd behavior. Higher, steady specific gravity are appreciated, closer to 1.025; maybe due to their close association with invertebrates?
I'd like to mention that holocentrids produce audible sound, above and below water. They grind their pharyngeal teeth and stretch muscles against their long gas bladders; much like rubbing your fingers along a balloon. I
I'd shy on making it brisk. These fishes are found in areas where the water really whips at times.
For a really outstanding arrangement, provide a large dark cave-space with two openings and a group of these fishes and others they are found with in the wild. The under ledge and cover sub-habitat is a rich biotope in the reef world.
Generally not. Squirrelfishes live comfortably alone as adults. In the wild most live in aggregations as young.
Best put in established systems, keeping light on but subdued for a couple of days.
Most Squirrelfishes as individuals get along with their own kind, other species of Squirrelfishes and other tankmates. Most would-be predators give them wide berth after looking over their overall spininess.
Think twice size-wise about using squirrels as reef-tank organisms. They are supreme choices as being hardy and interesting, but will greedily swallow any and all crustaceans that can fit into their expansive mouths. If you lack and do not intend to have shrimp(s) or crab(s), and would like to minimize bristle and other worm activity, consider a squirrelfish.
Reproduction, Sexual Differentiation/Growing Your Own:
See citations below for chance spawning reports of the related family of monocentrids. Squirrelfishes are indistinguishable externally as male, female.
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
They are predators on small very small fishes and mobile invertebrates, principally crustaceans in the wild. Livebearers, shrimp and other fresh and frozen meaty foods are acceptable; avoid pellets, flake and other dry prepared foods; these will not sustain them.
If your specimens are new, refusing food, or go on a feeding strike, execute a large water change and try a live shrimp with the lights off on the system. Generally Squirrelfishes can be trained to take 'wiggled' krill or other shrimp.
Disease: Infectious, Parasitic, Nutritional, Genetic, Social
These fishes are generally received free of external parasites, and clean up easily with routine freshwater dips and quarantine. The usual protozoan scourges of tropical marine fishes can be handily defeated if detected early enough with standard copper remedies.
To Spanish-speaking countries they're saldados or matajuelo; to the French: malais, in Hawaii: alaihi. To you and I they are the aptly named Squirrelfishes and Soldierfishes, the Holocentridae. Good aquaria specimens, whose only demands are meaty foods and a place to hide.
Burgess, Warren E., 1975. Salts from the seven seas (about Pineconefishes). TFH 6/75.
Chlupaty, Peter, 1982. Keeping Australian pinecone fish. TFH 4/82.
DeGiorgis, Joseph A. 1987. The longspine squirrelfish, Holocentrus rufus, FAMA 2/87.
Hemdal, Jay, 1986. The Flashlight Fish, FAMA 11/86.
Howe, Jeffrey C. 1994. Original descriptions, Sargocentron marisrubri Randall et al. 1989, Beryciformes, Holocentridae, FAMA 6/94.
Nelson, Joseph S. Fishes of the World, 3rd Ed., 1994. Wiley & Sons.