Yellow tangs are beautiful saltwater fish that are popular with aquarium enthusiasts due to their ease of care and beautiful, bright coloration.

Yellow tangs can sometimes be aggressive or territorial, but determining the tang’s sex can often help to bring together a more peaceful school of fish.

Male vs Female Yellow Tang

Size

Yellow tangs grow to about 8 inches long, and in general, males are a bit larger than females.

However, this size difference can be small, and many yellow tang owners see no size difference or even report that their female fish are larger.

Looking at size is often a good first step when it comes to sexing these fish, but it’s not a definitive indicator.

Male yellow tang fish

Setae

One of the easiest ways to tell if a yellow tang is a male or female is by looking at the setae.

The setae are stiff, bristle-like spikes or hairs located just before the tail fin of the fish. Yellow tangs can use the setae as a kind of defensive barb, and in young fish, the setae even contain venom.

In female yellow tangs, the setae are the same color as the fish’s body, and they can be difficult to spot. In some females, the setae may not be present at all.

In males, however, the setae are white. It often looks as if the fish has a short clump of white hair or rough scales right near its tail fin.

white mark on tail of male yellow tang

Cloaca

Another way to determine if a fish is male or female is to look at the cloaca or the reproductive opening. All yellow tangs have a cloaca, and they can look very similar.

However, the opening of a female fish is often a bit larger than that of a male fish.

Body Shape

In many fish species, females tend to have rounder bodies. This round shape can become pronounced during the breeding season, as the female becomes gravid with eggs.

In yellow tangs, a difference in body shape is much less noticeable, as yellow tangs develop gametes instead of eggs, but you may sometimes notice that females are slightly rounder than males.

round body male yellow tang

Shimmer Behavior

When male and female yellow tangs are housed together in large aquariums, they can sometimes display mating ritual behaviors.

Females change very little during mating rituals, but the color of a male yellow tang changes when they attempt to attract females.

Males will become brighter or their colors might change, and they perform a shimmering movement that helps to catch the female’s attention.

Breeding Behavior

Yellow tangs almost never successfully breed in captivity. This is largely because, once the fertilized eggs have hatched, the baby fish need to feed on micro foods such as plankton, and they generally can’t survive in the home aquarium.

However, yellow tang owners may occasionally see their fish performing breeding rituals. When breeding occurs, male and female yellow tangs rise to the water’s surface in an arc before releasing their individual gametes.

Males will often rise to the surface several times with different fish, but female yellow tangs only breed once during a particular cycle.

If you see a fish repeatedly engaging in breeding behavior during the same cycle, it’s most likely a male.

several yellow tangs together

Aggression

Yellow tangs are known as some of the most peaceful fish species, but they can still be aggressive towards other tangs or even members of their own species.

It’s often recommended that only one yellow tang be housed in an aquarium, although yellow tangs can sometimes be kept together in very large aquariums as long as they’re introduced as juveniles.

Both male and female yellow tangs can be territorial, but males are sometimes a bit more aggressive than females, and they may nip more frequently at other fish, particularly during feeding times.

Yellow tangs might also occasionally flair their fins at each other or other fish, particularly other tangs species. This behavior is slightly more common in male fish.

Although they’re considered to be peaceful, yellow tangs all have different personalities, and because they have sharp barbs, tangs can sometimes severally injure other aquarium fish.

It’s always important to carefully observe new fish and to keep an eye on yellow tangs as they mature and develop new territorial instincts.

yellow tang hiding behind rocks

Social Traits

Both male and female yellow tangs are relatively timid fish. They are active, so they require a large amount of open space for swimming, but they often spend a good deal of time hiding behind rocks, in caves, or in plants.

Whether you have a male or female tang, it’s best to offer plenty of hiding places and to keep the tang with only peaceful fish.

Because tangs can become aggressive or stressed during feedings, it’s important to offer plenty of food.

It’s also a good idea to provide a constant food source, such as strips of nori seaweed, which the fish can nibble on throughout the day and in between feedings of other foods.

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