Overview
The blue tang, or regal tang, is a bright royal-blue reef fish of the Indo-Pacific and a member of the surgeonfish family. It grazes algae across the reef by day and wedges itself into a crack to sleep at night.
Made famous as 'Dory', it is a beautiful but demanding aquarium fish: it grows surprisingly large, needs a lot of swimming room, and is prone to disease if stressed.
| Care level | Advanced |
| Adult size | 10-12 in (25-30 cm) |
| Lifespan | 8-20 years |
| Temperament | Mostly peaceful |
| Min. tank | 100+ gal (380 L) reef |
| Water | Saltwater reef |
| Temperature | 72-82°F (22-28°C) |
| Diet | Herbivore (algae) |
| Home aquarium? | Yes, but needs a big tank |
The surgeon's scalpel
Surgeonfish are named for a scalpel-sharp spine on each side of the tail base. The blue tang can flick these blades out to slash at a rival or a predator, so it is best admired, not handled.
Life on the reef
By day it roams in loose groups grazing algae off rock and coral, an important job that keeps reefs from being smothered. When threatened it can dart into a crevice and even lie on its side, playing dead, until danger passes.
Diet
Blue tangs are grazing herbivores. In a tank they need plenty of marine algae and seaweed (nori) alongside prepared foods, and the constant grazing keeps them healthy and colourful.
In the aquarium
A stunning fish, but one that reaches a foot long and needs a large, established reef with open water to cruise. They are notably prone to marine ich when stressed, so stable water and a big tank are essential.
Fun facts
- Surgeonfish get their name from scalpel-like spines at the base of the tail, which the blue tang can flick out to defend itself.
- It is the real-life 'Dory' from the movies, properly called a regal or blue tang.
- When frightened it can lie on its side and play dead until a predator loses interest.
- Grazing tangs help keep reefs healthy by stopping algae from overgrowing the coral.
- A blue tang can live for well over a decade, and sometimes far longer, in a well-kept tank.
Frequently asked questions
Is Dory a blue tang?
Yes. Dory is a regal blue tang, Paracanthurus hepatus, the same royal-blue surgeonfish described here.
Can I keep a blue tang at home?
Yes, but only in a large, established saltwater reef tank of at least 100 gallons. They grow to a foot long, need lots of swimming space and are prone to disease if stressed.
Are blue tangs dangerous?
Only if handled carelessly. The scalpel-like spines at the base of the tail are sharp and can give a nasty cut, so they are admired rather than touched.
What do blue tangs eat?
They are herbivores that graze algae. In an aquarium they need marine algae and dried seaweed (nori) plus prepared foods to stay healthy.
