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"Oy, como esta mi par-eh Jo" (Hey, how's it going my friend, phonetically in Tagalog, the national language of the Philippines). "Hey, where's that strange Rabbitfish I brought up a few minutes back?" It's not in the holding bucket or on the bottom of the boat, hmmm. "Ricardo! What are you doing?!" "Dude, you're eating my fish!"
Yes, Dear Reader, this scene actually occurred in the sixties when I was a pet-fish lad. It was (and probably still is) not uncommon for fish "not on the list" for collection to end-up as very fresh meals. The Rabbitfishes, though often beautiful, interesting behaviorally, and quite hardy aquarium fare have the misfortune of being delicious.
If you've spent any time looking through fish magazines and books you know that there are far more types of "fishes in the sea" than offered to the hobby. Ever ask yourself, "Why is that?" Maybe other kinds of aquatic life are, un-catchable, shippable, uneconomical, too hard to keep??? Well, it ain't necessarily so. I'm here to tell you that there are MANY more fishes, not to mention non-fishes that can and will be added to the markets over time. This article is an attempt at speeding up that rate for one family, the Rabbitfishes. But for one possibly problematical trait (venomous fin spines) these fishes make great aquarium additions.
Classification: Taxonomy, Relation With Other Groups
Depending on which writers you favor there is one genus (Siganus) and two sub-genera, or elevating those two, two genera (Siganus and Lo); the former with 22 species, the latter with five. All have a, well... typical "rabbit-face" appearance and body plan. Lagomorph similarities include small, apical hare-like mouths, large, dark eyes and reserved temperament.
Their pelvic fins bear two stout spines with three soft rays between them; a unique trait among fishes; they have a long, single dorsal fin with 13 spines followed by 10 soft rays; an anal fin with 7 spines and 9 soft rays. I mention this detail to (re)emphasize the point that the Siganids spiny rays are venomous. These can and do easily puncture unwary aquarists hands while net-handling, so beware.
Siganids are members of the Suborder Acanthuroidei which includes some families of similar fishes (in terms of feeding, appearance, behavior) that you're probably familiar with; the Scats (Scatophagidae), Spadefishes (Ephippidae), Surgeons/Tangs/Doctorfishes (Acanthuridae), and the difficult-to-keep Moorish Idol (Zanclidae).
Rabbitfishes are almost all marine (one species is brackish), ranging widely in the tropical Indo-Pacific and eastern Mediterranean in shallow lagoons.
Some species to eighteen inches (50 cm.), rarely half that in captivity; slow to moderate growers.
Periodically other species of Siganids are offered, and their lack of inclusion here and in the industry should not dissuade you from trying them. None have proven to be difficult when received in good condition and met half-way in their requirements.
Selection: General to Specific
Size is a strong criterion; smaller individuals are more colorful and adapt more readily to the vagaries of aquarium life. An ideal range for purchase is somewhere between 3-4 inches overall length.
Color can be deceiving as individuals are very labile in changing such with their immediate mood. A "happy" specimen is to be selected for, but don't necessarily disqualify a fish as unsuitable due to temporary fright or nighttime coloration; they change dramatically and fast.
Of the twenty seven described species, 13 are open-range schooling, with the other 14 mainly living among coral reefs. How to tell which you're looking at? Trust your dealer, read up, look at enough printed images, get a very large tank... The species currently offered in the trade (and all the others I've had occasion to view in Public Aquariums) generally adapt supremely to captive conditions. All should be offered sufficient caves and crannies for shelter.
Rabbitfishes are not particularly fussy as regards general water quality. Due to their continuous daytime browsing and waste production, medium to strong circulation and power filtration is a plus.
Of the few dozen species of marine fishes our service company used, the Foxface, Lo vulpinis was a ready favorite. Though shy, its inquisitive nature and bright pattern made it a finger-pointing favorite of customers and their visitors. Two conditions allowed for successful keeping and show; a large, and stress-free environment. Physically the tank has to be big for swimming and growing space; and emotionally tankmates have to be matched that are not too rambunctious. We employed many 75 and 90 hexagons and 60 plus gallon regular tanks with Lions, gentler Tangs and Batfishes with Rabbits.
Due to their venomous spines and readiness to use them, most predators give Rabbitfishes wide berth; alternatively, they are typically casual toward other fishes... with one exception; members of their own kind. Though many species school together in the wild and may be presented to you as more than one to a tank at the dealers, you are best advised to maintain them solitarily (or as a pair if they are) unless blessed with a system of several hundred to thousands of gallons in volume.
If you must have more than one specimen, or species of siganid, provide plenty of crevices, do your best to place them all at once, and/or select individuals of different size.
First a note re netting: as with other venomous aquatics, I strongly suggest you utilize two nets to direct these fishes into a stationary underwater container (jar, specimen box, bag), rather than lifting the animal into the air. Do not risk painful envenomation by cradling or placing your hand in harms way, gloved or not. Punctures are painful, immediately, and may require medical inspection.
Once the fish is "home" it is best placed and left alone unfed in an unlighted system for a day. Rabbitfishes are one of my exceptions to the general rule of quarantine; most are clean and ready to go with just a preventative freshwater dip. Put another way, moving them again is not worth the damage that the small potential for disaster warrants from simple introduction to the main/display system.
Rabbitfishes are not to be trusted with non-fishes as their grazing habits often extend to macro-algae, and invertebrates of all kinds. If you employ a small individual to keep your reef system tidy, do keep your eye on it should it sample your corals, et al to destruction.
Reproduction, Sexual Differentiation/Growing Your Own:
There are reports of aquarium captive spawning brought on by changes in water depth and salinity; and evidence of estuarine reproduction in the wild in some species. Several species are regularly spawned by mariculture concerns as food fishes.
Like the other families in their suborder (see above), siganid young pass through a transparent planktonic larval stage termed the acronurus.
Some species show difference in color and size, females being slightly larger, less colorful, when about the same size and age.
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
Rabbitfishes have small mouths specially adapted for browsing on their principal food, algae. They must have rough or prepared vegetable material in their diet daily. This is not to dissuade you from offering meaty, flake or even pelletized foods as these are largely accepted; but without their greens Siganids tend to dwindle and fade.
Disease: Infectious, Parasitic, Nutritional, Genetic, Social
The Rabbitfishes are amongst the most sturdy, disease-free animals the hobby can get; they are generally the last in the tank to die from any given cause.
The Rabbitfishes are not as showy or outgoing as marine Angels or Butterflyfishes, but don't pass them off as undesirable aquarium specimens. They readily adapt and make hardy additions; just remember the poison glands at the base of their spiny rayed fins when handling these fishes.
Baensch, Hans & Helmut Debelius, 1994.Marine Atlas, v. 1.. Mergus, Germany.
Burgess, Warren E., 1977. The genus Lo. TFH 10/77.
Burgess, Warren E., Herbert R. Axelrod & Raymond E. Hunziker III, 1990. T.F.H. Publications, Inc. NJ.
Jones, Lawrence Lee Cooke, 1981. A review of the Rabbitfishes. FAMA 10/81.
Nelson, Joseph S., 1994. Fishes of the World, 3rd Ed. John Wiley & Sons, NY.
Taylor, Edward C., 1983. Rabbitfishes for your marine tank. TFH 2/83.