LONGFIN BATFISH
(Longfin Spadefish)
Platax teira (Forsskal, 1775)
Family Ephippidae
Now here's a find! On 15 Dec. 2003 Bo Lusher and Andy Schwanke at Mike Severns Diving, operating out of Kihei, Maui, saw this batfish at a rarely-dived site near Pu'u Ola'i at a depth of 85 ft. Since everyone knows that batfish do not occur in Hawai`i, the sighting was unusual, to say the least. The following day they went back to locate it again, but it wasn't there. The day after that, however, they saw it at the wreck of the St. Anthony about 3 miles away, where Pauline Fiene snapped this shot. Since Andy had photographed it the first day, it was easily identified as the same individual fish by the identical markings and tears in the fins.
      My theory is that it's an aquarium release. (People buy them when they're small, and release them when they outgrow the tank. Of course no one should EVER release an alien species into our waters--but it does happen.) Longfin Batfish are schooling fish and this one was probably roving far and wide in search of others of its kind. Maui has a long coastline and the odds of the same dive boat finding the same wandering fish again must be almost as bad as the odds of  the batfish finding a mate in Hawaii.
      I said earlier that batfish do not occur in Hawaii. Strictly speaking, that's not true. In April 1980 several Golden Batfish (Platax boersii) were seen under the cargo pier at Midway Atoll over 1000 miles northwest of the main Hawaiian Islands. One was speared and its identity confirmed. As far as I know, the species has not been reported again in the Hawaiian chain. It would be almost impossible for the Midway specimens to have been aquarium releases. What probably happened was that some Golden Batfish larvae drifted into Hawaiian waters via the Kuroshio Current from Japan. A few grew to maturity, but did not succeed in reproducing here. Of course, drifting larvae could be the origin of this Longfin Batfish as well--evidently, this is not the first time the species has been seen in Hawaii. We'll probably never know unless more of them turn up.
    If you see a batfish, how do you know if it's a Golden Batfish or a Longfin Batfish? The two are similar, but the Golden Batfish, as it's name implies, has a yellowish tinge overall. The best way to identify the Longfin is by the dark spot low on the body above the ventral fins. There is often a narrow vertical dark mark just behind it. Both are clearly visible in this photo.
    By the way, many ichthyologists seem to prefer calling fishes of this genus "spadefishes" on the grounds that fishes of the somewhat obscure family Ogcocephalidae are also called "batfishes." However, the term "batfish" in reference to the large, common, and showy fishes of the genus Platax (family Ephippidae) is firmly entrenched among divers and aquarists. The problem is easily solved by calling the Ogcocephalid fishes "walking batfishes," as suggested by Scott Michael; this name is actually quite descriptive of these crawling bottom-dwellers.

Update April 2005: Longfin Batfish have recently been seen off O`ahu. One appeared at the wreck of the Sea Tiger, off Waikiki, and Brian Zgliczynski reports seeing several, possibly three, at the offshore moi cages (where moi, or threadfins, are raised commercially). The species may be here to stay. Bill Keen of Bill's Dive Locker took the photo below of the Sea Tiger batfish. The photo was taken in February 2005 and kindly sent to me by Rill Partlow of See in Sea Scuba.

Longfin Batfish and Hawaiian Cleaner Wrasse - Bill Keen - Sea Tiger wreck