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Amongst the best choices in "character" specimens to build a collection around are four of the batfishes of the genus Platax. They're intelligent, playful and in other ways about as close as one can get to the aquarium equivalent of the family dog. Believe it or not, I've seen some do tricks and retrieve objects!
Such can't be stated for the other members of the family, collectively labeled Spadefishes (a common name for the Batfishes as well). They tend to be nervous types, and poorly adapt to captivity as one notorious Platax does.
Classification: Taxonomy, Relation With Other Groups
The Spadefishes (including the Bats) are part of the largest Order of fishes, Perciformes. They are further classed in the Suborder Acanthuroidei, which should sound familiar. This group includes the Surgeon/Doctorfishes/Tangs, Family Acanthuridae of course as well as those aquarium favorites the Scats (Family Scatophagidae) and Rabbitfishes (Siganidae).
Our Family of concern, the Ephippidae comprise some seven genera with roughly twenty species. Most of these fishes have prominent vertical stripes as young, hence the family moniker, ep- and hipp- mean "upon the horse", as in a saddle; neat huh? Since we want to dismiss the "rest" of the ephippids, as Spadefishes of little/no use to home aquarists, and get on with those that are (Platax), a sure way to distinguish the former is that their dorsal fins spinous portion is distinct from the continuing soft rayed part. In Batfishes, the two dorsal segments are continuous.
Species of Use/Availability to Aquarists:
The "other than Platax" Spadefishes can be summarily ignored by aquarists on a handful of damning characteristics. 1) They're very skittish in captivity; nervousness showing in difficulty in adjusting to small volumes, poor eating, "mysterious" deaths. 2) They're really only happy in groups... and 3) They get pretty darned big, some more than two feet long, and at least that tall.
Genus Platax: Of the genus Platax's five species, four are almost sure winners for large fish-only tank additions; and the fourth a dismal doomed challenge.
The Boers Batfish, Platax boersii also makes a fantastic aquarium showpieces, but is all too rarely offered for sale in the trade. Boer's Batfish is very similar to Platax tiera when young, able to be distinguished by its relatively shorter dorsal and anal finnage. Adults look a lot like Platax orbicularis with more yellow caudals.
The whole family of Spadefishes are marine, with some making occasional feeding forays into brackish. They are found in coastal waters of the Atlantic, Indian and Pacific Oceans.
If you can get one to live, the Pinnatus tops out at about 14 inches (35 cm) in length. The other four Platax grow to close to two feet long overall in the wild.
Selection: General to Specific
Other than Platax pinnatus, healthy juvenile Batfishes offered for sale are easy to pick out; they're either good or dead. Really, there are few in-betweens. Here's a couple of things to judge try-outs by:
1) Size; you want to get a small-as-practical specimen and feed it sparingly to keep it reasonably so. All Platax are cute and elongated vertically in appearance due to long flowing dorsal and ventral finnage; and all turn into spade-shaped silver with black bar behemoths. The best size? One that is just large enough to be able to fend for itself against the rest of your tanks livestock; they're tough even when tiny, and make food available more frequent in small volumes.
2) Feeding; a good general criterion. Make sure the prospective purchase is at least vital and outgoing enough to be feeding.
3) Disease Free: batfishes are more susceptible than average to infectious diseases like ich, and shipping/handling traumas as in cuts and bruising; and happily, more than average in healing up. Nonetheless, look them over carefully.
4) BTW, re moving these fishes, when they're larger, not only is there a good chance of tearing their unpaired fins, but tremendous psychological damage in changing them to new environs. If at all possible, dispense with net-raising large Platax from the water, instead directing them into a submersed bag and carefully lift same with the batfish inside. Much better.
Can you say, BIG? You and your batfish need a large tank. It will get some-teen inches tall in a matter of months and so the aquarium has to be at least that tall. A fifty five gallon "show", in my opinion, is an absolute minimum size/volume.
Similarly, as yours grows it will need lots of open space. If using a large hexagon or other odd-shaped system, concentrate the decor to the back middle.
Not finicky types where water quality is concerned, Platax do fine under "common" conditions for marine tropical fishes; specific gravity in the low 1.02's, temperatures in the seventies to low eighties. Emphasis should be paid to regular gravel vacuuming and water changes; ten to twenty five percent every week if possible, and more than adequate filtration/circulation/aeration.
As very small young individuals you may find batfishes laying down at the bottom or surface looking like another of their namesakes, Leaffish. Don't let this throw you; it is a natural camouflage behavior.
Due to high metabolism, copious amounts of food eaten and defecated, you'll want a serious outside power filter system. One incorporating a easily changed mechanical component for removing solids. And oversized pump and/or air circulation and aeration.
Not at all agonistic toward their or other species given enough room and food. Can you have too much money, too large a computer hard drive, too high an Intelligence Quotient? You can't have too large an aquarium either.
Standard acclimation techniques apply with ephippids. You may well find that your new specimen is hiding among the decor for a day or so. Coaxing it out with live food is the answer to the question of how to initiate interactive behavior.
Batfishes will not eat any but the smallest of fishes, but willingly sample most invertebrates; they're strictly for fish-only systems. Conversely, fast-moving and nipping types (e.g. Triggers, large Angels, Puffers) may chew their flowing fins beyond distraction.
Reproduction, Sexual Differentiation:
Though not known, ephippids are thought to be pelagic spawners, releasing their gametes as a school, cued by moonlight and tides. Lucky larvae make their way to quiet coastal waters and develop, depending on species, as pelagic or benthic fishes.
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
In the wild, foods include algae, several types of invertebrates, including jellyfishes, crustaceans and worms. In the wild, the for-aquarium-use Platax, i.e. all but Platax pinnatus, greedily accept any and all foodstuffs, in every conceivable format (dried, frozen, flake, freeze-dried, fresh, fricasseed...) in almost unlimited quantity. Take care to not overfeed your batfish, devising some means of ensuring tankmates get their share.
Disease: Infectious, Parasitic, Nutritional, Genetic, Social
Ephippids respond well to specific gravity manipulation and copper-based medication treatments. One notable reaction to chemical exposure is their prodigious mucus production and shedding. This is a normal reaction but a clear warning sign if it occurs when you have done nothing to bring it on. Platax with sores on their sides, fins drooped back, inactive, are in trouble... quickly assess what the causes are and act. Water changes to a lower specific gravity (a few thousandths if your other livestock can tolerate such a shift) may be your best move.
Like the addition of a dog to your family, the acquisition of an appropriate Batfish species is a long-term proposition. They are hardy, eager eaters and growers; so do make plans for larger quarters.
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Burgess, Warren E., Herbert R. Axelrod & Raymond E. Hunziker. 1990. Atlas of Aquarium Fishes Reference Book, v.2, Marine Fishes. T.F.H. Publications, Inc. NJ. 768pp.
Campbell, Douglas G. 1979. Fishes for the beginner, pt. 6 (batfishes). FAMA 5/79.
Hemdal, Jay. 1985. The pinnatus batfish: Force feeding, a new idea for maintaining this species? FAMA 10/85.
Kuiter, Rudie H. & Helmut Debelius. 1994. Southeast Asia Tropical Fish Guide. Tetra-Press, VA. 321pp.
Nelson, Joseph S. 1994. Fishes of the World. John Wiley & Sons, NY. 600pp.
Siegel, Terry. 1971. Fish of the month (batfishes). Marine Aquarist 2(1):71.
Taylor, Edward C. 1982. Batfish in your aquarium. TFH 9/82.