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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

By Bob Fenner

Myripristis violacea  

     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.

Size:

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.

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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.

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Genus Myripristis

Myripristis adusta Bleeker 1853, the Shadowfin Soldierfish. Widely distributed in the Indo-Pacific. To fourteen inches in length in the wild. Occasionally caught and sold for aquarium use. A more nocturnal species. These ones in Fiji in the Pacific and the Maldives, Indian Ocean.
Myripristis amaena (Castelnau 1873), the Brick Soldierfish. West-Central Pacific; Indonesia, Philippines to Hawaii. To about ten inches in length. Monterey Bay Aquarium photo.

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Myripristis berndti Jordan & Evermann 1903, the Blotcheye Soldierfish. Indo-Pacific, including eastern Pacific in distribution. To one foot maximum length. Best from Hawai'i.

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Myripristis jacobus Cuvier 1829, the Blackbar Soldierfish. Tropical West Atlantic. To ten inches maximum length. These images shot in the Bahamas. 15-60 feet. 

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Myripristis kuntee Valenciennes 1831, Shoulder-bar Soldierfish. Indo-Pacific; East Africa to Hawai'i. Two to 55 meters. To eight inches total length. Reef-associated. Leading part of spiny dorsal fin yellowish. One off of Queensland, Australia, another off Hawa'i's Big Island.

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Myripristis leiognathus, the Panamic Soldierfish. Cortez to Ecuador, TEP; to 7 inches. Here in Puerto Vallarta 2015

Myripristis murdjan (Forsskal 1775), the Pinecone Soldierfish. Indo-Pacific through Oceania. Characterized by white edges on the unpaired and pelvic fin edges and brown margin on the gill cover. To one foot total length. This one photographed in the upper Red Sea where it is caught for the European hobby.

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Myripristis violacea Bleeker 1851, the Latticework Soldierfish. Indo-Pacific, to nine inches in length. A good-looking smaller species that ought to be more used in the aquarium interest. This one in Fiji.

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Myripristis vittata Valenciennes 1831, the Whitetip Soldierfish. Indo-Pacific. To ten inches long. Another under-utilized species available in good numbers. Like most Soldierfishes, feeds on motile invertebrates at night. Maldives and QLD, Australia specimens.

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Genus Neoniphon

Neoniphon marianus (Cuvier 1829), the Longjaw Squirrelfish. Tropical West Atlantic. To seven inches in length. Distinctive yellow body lines. This one in Jamaica.

http://fishbase.sinica.edu.tw/Summary
/SpeciesSummary.php?id=3249

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Neoniphon opercularis (Valenciennes 1831), the Black Squirrelfish, distinguished by the continuous hard dorsal being black in color. Indo-Pacific, east Africa to Micronesia. Fourteen inches maximum length. This one in the Maldives.

Neoniphon sammara (Forsskal 1775), the Sammara Soldierfish. Indo-Pacific, Red Sea to the Hawaiian Islands. To about a foot long. An occasional import. The first one in Hawaii, then the Cooks, last in the Red Sea.

Genus Sargocentron

Sargocentron caudimaculatum (Ruppell 1838), the White-tail Squirrelfish. Indo-Pacific; Red Sea to Polynesia. To ten inches in length. Live in and about caves, crannies in groups by day, turning all red and spreading over the reef to feed by night. 

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Sargocentron diadema Lacepede 1802, the Crown Squirrelfish. Indo-Pacific, Red Sea to Hawai'i. To nine inches in length. The most common Pacific offering in the family. Very similar to Sargocentron xantheryhthrum, but diadema has a very dark dorsal fine with a white stripe in its lower area, xantherythrum with a red dorsal with white spine tips. 

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Sargocentron melanospilos (Bleeker 1858), the Blackspot Squirrelfish. To 25 cm. Fiji 2017

Sargocentron rubrum (Forsskal 1775), the Redcoat. Indo-West Pacific, including the Red Sea. To eleven inches in length. These ones off of Heron Island, Great Barrier Reef, Australia.

Sargocentron spiniferum (Forsskal 1775), the Sabre Squirrelfish. A beauty, but often lost to trauma in capture and shipping and too large for most systems (to eighteen inches in length). The first image made in the Maldives, the second in the Gulf of Aqaba, Red Sea.

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Sargocentron suborbitalis (Gill 1864), the Tinsel Squirrelfish. Sea of Cortez to Ecuador. To 25 cm.

Sargocentron violaceum (Bleeker 1853), the Violet  Indo-Pacific; Aldabra to S. Japan, GBR, Micronesia. To 45 cm. in length. Live in and about caves, singly by day, Feed by night on crustaceans and polychaetes. Sulawesi pic.  http://fishbase.sinica.edu.tw/Country/CountrySpeciesSummary.cfm?Country=Indonesia&Genus=Sargocentron&Species=violaceum

 

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.

Environmental: Conditions

Habitat

 Can you replicate the hiding netherworld of ledges and coves by day, the bottom, food searching, nocturnal swimming space by night? 

Chemical/Physical  

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? 

Biology/Other

 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

Filtration  

I'd shy on making it brisk. These fishes are found in areas where the water really whips at times. 

Display 

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.

 Behavior:

Territoriality  

Generally not. Squirrelfishes live comfortably alone as adults. In the wild most live in aggregations as young. 

Introduction/Acclimation  

Best put in established systems, keeping light on but subdued for a couple of days. 

Predator/Prey Relations 

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.

Summary:

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.

Bibliography/Further Reading:

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.

 

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