Clown Tang (Acanthurus lineatus)

The Clown Tang (Acanthurus lineatus), also called the Lined Surgeonfish, is one of the most dazzling fish on any reef: a yellow-orange body wrapped in electric blue horizontal stripes, each one edged in black, over a pale lavender belly. In the wild it patrols the surf zone, guarding a patch of algae-covered rock from every grazer that comes near. That same attitude comes home with it, and we want you to know what you are buying before you fall for the colors. Browse the rest of our saltwater livestock and supplies to plan the system around it.

Before You Buy

This is an advanced, aggressive fish. It grows to 14 to 15 inches, needs a 180 gallon or larger aquarium with at least 6 feet of swimming length, and is among the tangs most prone to ich and other parasites when stressed. It also carries a venomous spine on each side of the tail base that can deliver a painful sting. In an experienced keeper's large, mature, well-oxygenated system it is a breathtaking centerpiece. In a smaller or newer tank it is a fish that struggles and makes its tank mates struggle too.

Care Guide

• Tank size: 180 gallons minimum with 6 feet of length, and larger is better for an adult. It swims hard all day and needs room to patrol.
• Flow and oxygen: this is a surge-zone fish. Give it strong, varied water movement, a well-sized protein skimmer, and plenty of surface agitation.
• Water parameters: 72 to 78°F, pH 8.1 to 8.4, salinity 1.020 to 1.026. Clean, stable water is not optional with this species.
• Feeding: herbivore and grazer. Offer marine seaweed on a clip every day, an algae-based pellet, and some meaty frozen food a few times a week. A well-fed Clown Tang is healthier and noticeably calmer.
• Parasite prone: stress brings out ich and velvet quickly in this species. Quarantine every new fish in a separate tank before it goes in the display, and keep stress low with good feeding and plenty of rockwork.
• Add it last: introduce the Clown Tang after the rest of the community is established, so it does not claim the entire tank first.
• Handle with care: never net it or grab it by hand. Move it in a container, and keep hands clear of the tail spines when working in the tank.

Specifications

Compatibility

Reef safe, but not community friendly. It leaves corals, clams, and invertebrates alone. Fish are another matter: it is aggressive toward other tangs, surgeonfish, and any fish that grazes algae or shares its body shape, and it will harass them relentlessly. In most systems it should be the only Acanthurus, which rules out our Powder Blue Tang, Powder Brown Tang, and Convict Tang.

Better tank mates are robust fish that do not compete for its algae: a school of Blue Green Chromis, the Lamarck Angel, Ruby Anthias, and a Magnificent Foxface, which has venomous spines of its own and holds its ground. Add those fish first and the Clown Tang last.

Recommended Foods & Supplies

• Rod's Food Three Weed Blend seaweed for daily grazing
• Two Little Fishies SeaVeggies Green Seaweed on a VeggieMag Seaweed Clip
• Vitalis Marine Grazing Pellets, an algae-forward staple
• Selcon Vitamin Booster to soak seaweed and frozen foods for immune support
• Salifert Copper Test Kit and FritzMardel Coppersafe for treating in a separate hospital tank, never the reef display
• Innovative Marine AccuDrip Acclimator for a slow, low-stress introduction

FAQ

Is the spine really venomous?
Yes. The Clown Tang is one of the surgeonfish with venom associated with its tail spines. A cut is painful and slow to heal. Use a container to move it, and if you are stung, soak the area in hot water and see a doctor if pain or swelling is severe.

Does it really need 180 gallons?
Yes, and many experienced keepers go larger. It grows past a foot long, swims constantly, and becomes more aggressive when cramped.

Can it live with my other tang?
Usually not. It is very aggressive toward other tangs, especially other Acanthurus. Only very large systems with a carefully planned stocking order have a chance.

Why is it called prone to ich?
Clown Tangs react to stress quickly, and ich and velvet are often the first sign. Quarantine new fish, feed well, and keep water quality high to keep it healthy.

Is it reef safe?
Yes. It grazes algae and will not eat corals or invertebrates. The challenge is its behavior toward other fish, not its diet.