Tropical Fish Hobbyist - October 2010

Blotched Anthias Odontanthias borbonius

Occasionally imported for the aquarium trade, blotched anthias Odontanthias borbonius is a beautiful species that is generally found in deep water at depths in excess of 200 feet. Despite that, it does very well in shallow-water aquaria. Frozen mysis make an excellent first food and after your specimen starts taking that readily, other foods can be added to the diet. Blotched anthias are usually imported at about 3 inches in length and are suitable for 75-gallon or larger tanks. This is an active species that can grow to 6 inches in length.

While they are frequently seen as solitary individuals in the wild, they seem to be gregarious and will do well in groups. They can be kept with similarly sized fish and with most invertebrates, but should not be kept in brightly lit reef aquaria. The deep-dwelling lifestyle of O. borbonius in the wild gives us good indication that it will not appreciate bright lighting in the aquarium. In fact, it will tend to hide in caves if the light is too bright.

For a deep-water species, the blotched anthias has been known to science for a surprisingly long time and was originally described in

1828 by Valenciennes. It has a very broad natural range and can be found from the east coast of southern Africa to Palau in the South Pacific and north to Japan.

The problem with common names is that it can be difficult to know precisely which species one is referring to, and that problem becomes exacerbated for species that go by many. Paracanthurus hepatus is one such species. I have seen this species

sold as hippo tang, regal tang, palette tang, yellowtail tang, blue tang, and Pacific blue tang, and every one of those with the name “surgeon” inserted in place of “tang.” To make matters worse, many of those common names are used for completely different species of tangs as well!

This situation is further complicated by the existence of a second color morph, which features a yellow lower body (as seen above), so you can add “yellow belly” in front of most of the previously mentioned names. Following its use as the character Dory in Finding Nemo, this species is also sometimes referred to as the Dory tang. And all this for a fish that is currently the only species in its genus!

With that said, it wouldn’t surprise me if the two color forms are eventually given separate species status, as the trend in ichthyology today seems to be looking at smaller and smaller details and differentiating species at the DNA level, even when no external differences are apparent. The type specimen was from Ambon in Indonesia, so if the color forms are separated, it is the regular or blue form that will continue to be known as P. hepatus.

Pacific Blue Tang Paracanthurus hepatus

All that aside, this is a wonderful aquarium species. The blue of the Pacific blue tang has been compared favorably to that of the blue morpho butterflies, generally considered the bluest things on earth (leading to yet another occasionally used common name, the morpho tang). The blue form is more readily available in the trade, with most specimens originating from the Philippines or Indonesia.

The yellow-bellied form inhabits most of the east coast of Africa and usually reaches the aquarium trade in exports from Kenya. The extent and intensity of the yellow color on the belly increases with age. It is relatively insignificant in young individuals but becomes a bright yellow that covers the entire lower part of the body in adults.

P. hepatus has a reputation for being susceptible to Oodinium, so keeping it in a quarantine tank for the first month is always a good idea. In my experience, the blue form is more prone to Oodinium infections than the yellow-belly form.

Be prepared for odd behavior when you obtain your first specimen. I’ve gotten more phone calls from frantic hobbyists about this species in the first 48 hours after I’ve sold them than any other. They are very shy initially, and their idea of hiding includes lying on their sides and hiding upside down in the decorations. This is perfectly normal behavior. Over the next few weeks, they become much more comfortable in their environment and lose much of their initial shyness.

This is another good reason to keep them in a quarantine tank when you obtain them. If they are intimidated by other fish in a display tank, they may never feed well in the aquarium. In a quarantine tank, where there is no competition for food, they can more easily adjust to aquarium fare, increasing the chances they’ll be good eaters in the display tank.

Their natural diet consists in large part of plankton, so they are excellent additions to reef aquariums, as they will seldom bother any invertebrates. Of course, being tangs, they will also eat some algae and will ravenously devour romaine lettuce, nori, broccoli, etc.

This is a schooling species, particularly when young, so they can be kept in a group. When keeping more than one in a tank, I like to add at least four fish, which should all be about the same size and added at the same time. When two or three are added, sometimes