Acanthurus japonicus is known under numerous common names in English, including Powder brown tang, Powder brown surgeonfish, Powder black surgeon, Japan surgeonfish, White-nose surgeonfish, and White-faced surgeonfish.   

Acanthurus japonicus has not been evaluated for the IUCN Red List of Threatened Species.

Geographical range, habitat and habits

The Powder brown tang is found in the Indo-West Pacific, from the Ryukyu Islands of Japan to the Philippines and the island Sulawesi in Indonesia. It can be encountered in the following countries: Indonesia, Japan, Palau, the Philipines, and Taiwan.

The Powder brown tang inhabits clear lagoons and seaward reefs down to a depth of 20 meters / 66 feet. It prefers shallow exposed environments and forms small to large aggregations. 

Size and appearance

The largest scientifically measured Powder brown tang was 21.0 cm / 8.3 in.

The Powder brown tang has brown body and is adorned with a broad white band and a bright orange band. The white band stretches from the lower edge of the eye to the upper lip, while the orange band is located in the outer part of the soft portion of the dorsal fin. A wishbone-shaped yellow marking runs along the body. The caudal peduncle is yellow and the same colour is found on the base of the pectoral fins. Pectoral, anal and dorsal fins are dark brown with light blue highlights at the tips.

On each side of the caudal peduncle you will find a single spine, the so called scalpel. This sharp spine is used for defence and to establish dominance. When the spine is not in use, the fish will keep it folded down inside a groove.

The juvenile fish is light brown in the middle of the body and yellow at the top and bottom. The anal fin is yellow and dark brown, and the pectoral fin is adorned with a yellow dot. The face has white on it, but they are not as pronounced as in adult fish.

The Powder brown tang (Acanthurus japonicus) can be easily confused with its close relative the Gold-rimmed tang (Acanthurus nigricans) because they look very similar to each other. The Gold-rimmed tang has however only a patch of white under the eye, while the Powder brown tang has a white band that extends down to the lip.

Powder brown tang care

It is not recommended to house the Powder brown tang in an aquarium smaller than 75 gallons / 285 litres. It needs plenty of space for swimming as well as suitable hiding spots. Use rocks and/or corals to create crevices. Include live rocks in the set-up and encourage natural algae growth.  

The Powder brown tang is normally kept in peaceful community aquariums. Do not house it with other tangs, because they will most likely attack this peaceful and passive species. If you absolutely must keep it with tangs, chose one of the fairly peaceful species. Keeping more than one Powder brown tang is not recommended unless you have a huge and cleverly decorated aquarium.

The Powder brown tang is considered reef safe; it will normally leave both mobile and immobile invertebrates alone. It can however be a good idea to keep corals glued down because this large and powerful fish may accidentally overthrow them while swimming. 

Keep the water temperature at 72-78º F / 22-25 º C, the pH-value at 8.1-8, and the specific gravity at 1.020-1.025. Powerful water movement is strongly recommended. It is important to keep the oxygen level up.

The Powder brown tang is rather sensitive while it acclimatizes itself to a new home, but if you manage to keep it alive during this period it will normally become quite a sturdy aquarium inhabitant. It can be a finicky eater until it has grown accustomed to its new surroundings. You can find more info about feeding Powder brown tangs further down in this article.

Be careful when you handle your Powder brown tang, because the “scalpels” can inflict painful wounds. The pain may last for hours and there is a risk a swelling, discoloration and infection.

Feeding Powder brown tang

The Powder brown tang is primarily an herbivore that feeds on algae in the wild. It will however ingest tiny animals that live among the algae and it should therefore be given occasional servings of meaty foods in the aquarium.

Keep your Powder brown tang on varied diet. You can for instance combine spirulina flakes with fresh and dried marine algae and boiled vegetables such as broccoli, zucchini and carrots. Ideally include flakes or pellets rich in vitamin C in the diet. As mentioned above, you should also give your fish occasional servings for meaty foods, e.g. brine shrimp and mysid shrimps.

The Powder brown tang is a continuous feeder that will spend most of its time grazing. It is therefore better to give it many small portions of food throughout the day instead of just one or two big servings. Ideally place a vegetable clip / clothes-pin in the aquarium and constantly keep a peace of noori or similar there for the fish to nibble at. Natural algae growth should be encouraged in the aquarium. You can even culture macro algae, e.g. chaetomorphia, in the aquarium.

As mentioned earlier, the Powder brown tang can be a picky eater when it is trying to acclimatize itself to a new home. During this period, it is best to offer it plenty of marine macro algae since this is what it would eat in the wild. It is always a good idea to wait until you have an aquarium with prolific natural algae growth before you get a Powder brown tang. Also include a lot of crevices in the set-up because this will make the fish feel safer and more inclined to leave its hiding spot to feed.

Breeding Powder brown tang

It is hard to sex Powder brown tangs based on outer appearance.

This is a group spawning species and the spawning will typically take place in the evening. The fish will form a group and scatter eggs and sperm out in the open water. The eggs contain oil which keeps them afloat. After roughly 24 hours, the egg will hatch and a clear 2 mm long larva will emerge.

We do not have any information about breeding the Powder brown tang in aquariums.

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