News / Species Spotlight / Platax Batfish (03/28/12)

Platax Batfish

by Charles J. Hanley III

Scientific Name: Platax batavianus, P. orbicularis, P. pinnatus, P. tiera
Common Name(s): Batfish, Spadefish

Taxonomy:

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Ephippidae
Genus: Platax

Description:

With elegant names like Pinnate, Orbiculate, Zebra, and Longfin Teira, it might seem like batfish are wimpy little fish with long wispy tails and not much else. On the contrary, batfish are large, tough, and long-lived. They are also friendly and gentle, making them great community fish. Ordinarily I try to present a species or group which is maintainable by as broad a range of aquarists as possible. Todays installment, however, focuses on a group of fish which are not appropriate for all aquarists. Unfortunately, batfish are too big for most tanks. Nonetheless, they deserve some attention too, because they are fine candidates for inclusion in a marine fish-only system on the order of 200 gallons or more. Their unique body shapes, especially as juveniles, set them apart from most other marine fish. Batfish have been known to live as long as 14 years in captivity, and they develop their own personalities. They can even be taught to take food from your hand!

Batfish (Platax spp.) are closely related to sicklefish, scat, stripeys, and monos. The name originates from the cross-section of the sagittal plane, or side-view, of juvenile fish of the Platax genus (which looks very much like a bat in flight). That is, viewed from the side, juvenile Platax spp. resemble a bat with outstretched wings. The head of the bat would be at the tail of the fish. Interestingly, adult Platax do not look like bats, owing to a dramatic physiological morph that occurs at maturation. Adults look much more like a spade, which is why batfish are also called spadefish.

For larger aquariums, especially tall ones, it is important to fill the available space selectively. The filtration systems on large aquaria usually use high-efficiency mechanical equipment to reduce the filters footprint. Not surprisingly, it is wise to underload the capacity of a tank to avoid diseases and pathogens associated with overcrowding and deteriorating water quality. At the same time, if the space in a large tank isnt filled with well-distributed fish, it looks strange. It can be too empty in some areas and too busy in others. I like to use fish species that will give the water column a layered look, and batfish do this particularly well. I like them because they are big, silvery, eye-catching fish. A small school of batfish stands out, specifically because they tend to inhabit the upper third of the tank, leaving plenty of room for other tank mates nearer the bottom. They enhance the vertical dimensions of the aquarium through their tall profile and usage of space. Moreover, the height belies the relatively smaller biomass these fish add, due to their thinner transverse, or frontal, profile. In other words, they are tall and skinny, which makes them fill more space visually than they fill physically. The advantage is less pressure on the filtration system, which is often already hard-driven in larger systems.

Natural Habitat and Ecology:

Platax batfish are tropical, Indo-Pacific fish, with endemic areas ranging from the Red Sea east to Australia and the Great Barrier Reef. Some have been found as far north as the Japan. They are most often found on fringing fore-reefs, near the edge of deeper waters. Though omnivorous, batfish might best be described as grazerstaking advantage of opportunistic feeding chances whenever possible. While juveniles may also take up residence in shallower lagoon areas, adults show an inclination toward inhabiting deeper waters down to about 60 feet.

On an ecological level, batfish may be highly beneficial to wild coral reefs, as they are voracious algae eaters. In 2006, results of a study of the Great Barrier Reefs algae-eaters were released. It was determined that a single species of batfish, Platax pinnatus, was able to out-consume over 40 other species of endemic herbivorous fish.

Aquarium Care:

Batfish are gentle, community animals. They can be solitary or social, and are found exhibiting either behavior regime in the wild. In aquariums, batfish may do better with con-specific tank-mates, especially as juveniles. While they do reproduce sexually, they are not generally known to do so in captivity.

Juvenile specimens are highly sought-after due to their unique shape and coloration. During this time, specimens may be quite shy and it is recommended to house them with plenty of aquascaped hiding spots. Including several tank-mates of the same species will induce shoaling behavior, which enhances the comfort level of a given individual. This technique may be used to encourage feeding upon introduction. Wild caught batfish have been known to refuse food during acclimation and it is believed that the presence of con-specifics in the tank eases the transition to frozen foods. However, once batfish have grown accustomed to the food and the handler, they are quite friendly and hardy. They can be trained to take food from the hand and will also graze on algae and small animals. There have also been examples of batfish living as long as 14 years in captivity.

Keep in mind, this genus of fish is not recommended for anything but the biggest home systems. They will grow into impressively large individuals, some up to two feet long. They will also mature into much different looking fish. Adults are primarily silver, with rounded, spade-shaped bodies. The tall and narrow body-shape indicates that batfish are highly agile, but not fast or powerful swimmers. The shape lends itself to taller aquariums as opposed to large, long tanks.

As for water quality, standard saltwater parameters are acceptable. Saltwater fish tanks can be expected to carry minimal levels of nitrate, however nitrite and ammonia should never be allowed to build-up. A pH of 8.1-8.4 will suffice, as will normal salinities ranging from 1.021 to 1.024 S.G. Interestingly, batfish have been known to survive in brackish water, though it is probably safest to maintain salinity levels roughly equal to that of natural seawater. Medium to moderately bright lighting rounds out the remaining batfish requirements. These fish can be fed a variety of options, but should be offered omnivorous opportunities. They will eat small meaty parcels like mysid and brine shrimp, chopped up squid, and algal offerings. They will also graze on invertebrates such as those commensal to reef tanks. Therefore it is not recommended to house coral and batfish together.

Quick Notes:

  • Batfish need big tanks
  • Juveniles morph into large, very different looking adults
  • Provide con-specific tank-mates to ease the transition to aquarium life
  • Feed a variety of meat and algae, and be prepared to develop a long-term relationship

References:
Jennings, Greg. The New Encyclopedia of the Saltwater Aquarium. Buffalo : Firefly books Ltd., 2007.
Simon & Schuster. Simon & Schuster's Guide to Freshwater and Marine Aquarium Fishes. New York : Fireside Books, 1977.
Lieske, Ewald and R. MeyersCoral Reef Fishes, Revised EditionPrinceton University Press: Princeton, 2001.
Catherine Brahic. Batfish May Come to Great Barrier Reef's Rescue . New Scientist: Environment. http://www.newscientist.com/article/dn10819. 12/18/2006.