Commonly found in both saltwater and brackish waters, damselfish are best known for their low maintenance, colorful appearances, and easy adaptation. These explain why damselfish are so popular among both inexperienced and professional aquarists alike.

In case you wish to have some damselfish at your home tank, it is important to learn about their size, temperament, and other relevant factors. For example, how big do damselfish get? And how should you take care of these fish? The answer will be addressed right below!


How Big Do Damselfish Get?

On average, a typical damselfish has a length of roughly 3 inches. This is relatively small compared to most other species. Hence, you need not worry about whether damselfish can fit inside small tanks.

That said, there is a particular strand of damselfish that can grow up to 12 inches! They are called the Garibaldi, and they are arguably the biggest damselfish you can get.

Damselfish – What You Need To Know


Most damselfish have an elongated and flat body. Their tails are sharply forked and have a different shade from the entirety of their bodies. Damselfish also acquire two anal fins running under the belly, coupled with two nostrils on both sides of their heads.

As far as colors are concerned, damselfish stand out due to their vivid and unique hues. Some are born bright blue with an orange tail, while others enjoy yellow skin with reddish tails.

However, do not get all worked up about damselfish’s vibrant colors. Many of these species are a sight to behold when they are not fully mature only. Some will turn to a boring brown after reaching adulthood.

If you are not sure whether your newly purchased damselfish falls within this category, ask the seller for details.


Damselfish are not picky eaters at all. Since they are omnivores, feel free to drop anything inside the tank. But be sure to create a healthy mixture between protein and fiber.

Your fish need both to grow and remain active. If you are unsure what to feed them, look for minced fish, copepods, brine shrimp, brine shrimp eggs, squid, and worms.

Tank size

As damselfish are considered small and medium-sized fish only, you tend not to need much besides a 20-gallon aquarium. However, building up a community with at least one damselfish will require at least 30 gallons of water.

In the rare cases where you want to keep several damselfish along with different types of underwater animals, consider investing in a 100-gallon tank for optimal conditions.

Common varieties


Damselfish are just the umbrella term for different strands. Below are some of the most popular damselfish varieties you can find.

Yellowtail damselfish

As the name indicates, yellowtail damselfish stand out thanks to their yellow tails and deep blue bodies. They are quite mild in manners and are only 3 inches in length.

Azure damselfish

Also known as half-blue damselfish, Azure damselfish is blue for two-thirds of their bodies. Meanwhile, their belly is mostly covered in yellow or orange. They are 3 inches in length and are super easy to adapt to new environments, making them ideal for amateur aquarists.

Domino damselfish

With various white spots on their bodies, domino damselfish is visually stunning, especially when they swim around. However, they are slightly bigger than the other two, with a length of roughly 5 to 6 inches.

Domino damselfish are also notably hostile, so make sure to keep them away from other peaceful fish.

Blue damselfish

Blue damselfish are the easiest to come across due to their accessibility and vibrant colors. They also have the unique ability to turn black when they feel threatened.


1. What is the largest damselfish?

The largest damselfish belongs to the Garibaldi. While the average damselfish does not exceed the length of 12 inches, the Garibaldi can be 15 inches in length.

Garibaldi Damselfish

2. What fish can live with damsels?

Damselfish are known to be quite aggressive. They bite and snap around frequently, making them a highly difficult fish to live with others. Given how much of a bully damselfish are, you should consider giving damselfish a tank of their own.

Or, in case you can afford a larger tank where each fish gets plenty of territories, look for semi-hostile tank mates.

If the fish are too docile, they run the risk of being overpowered by damselfish. On the other hand, overly aggressive fish means the chances of direct collisions will significantly increase. You can go for bottom-dwelling gobies, dottybacks, dwarf angelfish, and clownfish to ensure a healthy community.

Also, there is the issue of introducing fish in the right order. You should put damselfish into the tank after all other species have already claimed their territory. This way, damselfish will not get close to other tank mates, preventing fights from the start.

Last but not least, if you are not worried about refilling invertebrates every once in a while, a few of them can be good for the tank. That said, do not be overly surprised if you ever find some of them disappearing!

3. Are damselfish aggressive?

Yes. Damselfish are among the most aggressive fish you can get for a home tank. Not only are they hostile towards other fish, but they can also bite your hands and injure you slightly! Look for their teeth and try to keep a safe distance between the fish and your fingers.

And, of course, if you intend to put damselfish with other species, find out about their compatibility level beforehand. This helps you minimize the percentage of conflicts in the long run.


So, how big do damselfish get? The answer is anywhere between 3 and 12 inches! Make sure to keep an eye on your damselfish and offer what they need in time, or else they will soon perish!

Alex is a pet freelance writer and editor with more than 10 years of experience. He attended Colorado State University, where he earned a Bachelor’s degree in Biology, which was where he first got some experience in animal nutrition. After graduating from University, Alex began sharing his knowledge as a freelance writer specializing in pets.

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