Best kept one per tank unless the system is very large
Diet
Omnivore, marine-algae-heavy
Time
High
Cost
High
Overview
The Regal Blue Tang is a large, active reef fish that grows far bigger and lives far longer than most buyers expect.
Reaching up to 30cm, it is a fast, near-constant swimmer that quickly outgrows the small tanks it is often sold for.
This is an advanced fish.
It needs a large, mature reef system, stable water, and an experienced keeper prepared for a decades-long, expensive commitment.
It is frequently sold to beginners who lack the space and equipment it requires.
Housing
Provide an established reef aquarium of at least 1100L (290 gallons) with a long open swimming area and live rock with caves it can dart into when stressed.
It is reef-safe and benefits from strong flow and good oxygenation.
Keep parameters stable: temperature 24-27C (75-81F), salinity 1.024-1.026, pH 8.1-8.4, ammonia and nitrite at zero, and nitrate low.
A fully cycled, biologically mature tank is essential before introduction.
Diet
Tangs are grazers that need a diet rich in marine algae.
Clip dried nori or seaweed sheets in the tank daily and offer good-quality marine flakes or pellets plus frozen mysis or brine for protein.
Vegetable matter should form the bulk of the intake.
Frequent grazing supports digestion and reduces aggression.
A varied diet with added vitamins helps prevent head and lateral line erosion (HLLE), which is linked to poor nutrition and water quality in tangs.
Health
Blue tangs are prone to marine ich (Cryptocaryon) and velvet, partly because of their thin scaling and sensitivity to stress.
Quarantine every new fish and minimise stress during transport and acclimation.
They tolerate copper-based treatment well, which is a useful tool in a hospital tank.
Watch for white spots, scratching, rapid breathing, and faded colour.
Head and lateral line erosion points to poor diet or water quality.
Stable conditions and good nutrition are the best preventatives.
Temperament
Generally peaceful toward other species but territorial toward other tangs and its own kind, especially in cramped quarters.
A single specimen per tank is safest unless the system is very large and well aquascaped.
Newly added fish are often shy and may hide or wedge into rocks.
With time and space they become bold, active centrepiece fish that need room to roam.
A good fit for
Experienced reef keepers with large systems
Hobbyists wanting a long-term centrepiece fish
Keepers committed to quarantine protocols
Those with the budget for a large setup
Common mistakes to avoid
Sold small, but grows to 30cm and outgrows small tanks
Prone to marine ich and velvet
Buying without a large, mature reef ready
Diet too low in algae causing HLLE
Is your enclosure big enough?
Minimum volume1,100 litres (291 US gallons)
CompanyMust be housed alone. Best kept one per tank unless the system is very large
In a reef, stability matters more than any single target number. A parameter moving fast does more damage than a parameter sitting slightly off.
Go now
Any detectable ammonia or nitriteWater change now with matched, mixed and aerated saltwater. Stop feeding. Directly toxic, and a marine system has less margin than a freshwater one.
Now
Temperature or salinity has moved sharplyCorrect slowly, over hours, not minutes. Check the heater and the top-off. The speed of the change does the damage. Correcting fast repeats the injury in the other direction.
Now
Rapid gilling, or a fish hanging in the flow breathing hardIncrease aeration and check temperature and salinity. Warm water holds less oxygen, and a heater failure shows up here first.
Now
Today
White spots, or a fine dusting like icing sugarIdentify which parasite before treating. Most reef tanks cannot be treated in place. The two common parasites look similar and need different handling; velvet can kill a tank in days.
Today
Corals closed for more than a day, or receding tissueTest alkalinity first, and compare it against the last reading rather than a target. Unstable alkalinity is the most commonly cited coral killer, and a swing shows up in the trend, never in a single point.
Today
A new fish added without quarantine now looks unwellRemove it to a separate system today if you can. Nearly every wipeout in a reef tank traces back to a skipped quarantine.
Today
Quarantine every new animal, including corals and inverts. It is the single practice that separates a reef that lasts from a reef that restarts.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Intermediate
Advanced
Beginner
Intermediate
Beginner
Beginner