Tangs and surgeonfish

Tangs swim constantly, so the minimum on each profile is really a statement about length. The tomini tang, at 6 inches (16 cm), is the smallest and lists 70 gallons (265 liters); a 4 foot tank is the floor for it, the kole tang and the scopas tang, and the yellow tang lists 100 gallons (380 liters). The sailfin tangs and most Acanthurus reach 10 to 16 inches (25 to 40 cm) and want 6 feet, which is the 125 to 180 gallon (470 to 680 liter) band most of the list sits in. The naso tangs reach 18 inches (45 cm) and list 180 gallons (680 liters); the vlamingi tang and the bluespine unicornfish reach 24 inches (60 cm) and list 360 to 400 gallons (1360 to 1500 liters). A tang sold at 2 inches in a 55 gallon looks fine for a year and then stops growing right, starts pacing the glass and picks fights.

Most tangs are territorial toward their own species and toward any other tang built like them. The working rule is one Zebrasoma, one bristletooth and one Acanthurus per tank, in a tank long enough for each to hold ground, added at the same time or smallest first. Two yellow tangs in a 125 gallon usually ends with one of them harried into a corner for good. The convict tang is the exception and the only tang in the list marked schooling: it is kept in groups and is the most peaceful of the family. The blue hippo tang is listed as social and tolerates its own kind better than most. Achilles, clown, powder blue and sohal tangs are marked aggressive, and a sohal or clown tang will run a 180 gallon tank. Every tang carries a blade on each side of the tail, a folding spine in most genera and fixed bony plates in the naso tangs, that cuts hands and nets; move them in a container, not a net.

Six tangs are marked difficult, for two different reasons. The powder blue, achilles and clown tangs and the blue hippo tang are ich magnets: they show marine ich before anything else in the tank, they need very clean, well oxygenated water with strong flow, and they need a proper quarantine before they go anywhere near a display. The hippo tang is also sold at 2 inches for a fish that reaches 12 inches (30 cm) and lists 180 gallons (680 liters). The bluespine and spotted unicornfish are difficult on size alone: 22 to 24 inches (55 to 60 cm) of fish that needs a system most homes cannot hold. The scopas and mimic tangs are the two the catalog marks easy, and the kole, tomini and yellow tangs are the usual first tangs once a tank has matured for a few months.

Tangs are grazers and lose condition fast on a meaty diet. Clip dried seaweed in the tank every day, feed an algae-based pellet or flake as the staple, and add mysis or other frozen food a few times a week for variety. The bristletooth tangs also work the rock and glass for film and detritus and do best in a tank that grows some. A tang with a pinched belly or a fading face is usually underfed before it is sick, and a well fed tang is far less likely to break down with ich when something else in the tank goes wrong.