Clownfish: Why Are They Swimming at the Top of the Tank? [5 Facts]

Just added a couple clownfish to your aquarium and wondering why are they swimming at the top of the tank? Well, there is no need to worry. They need some time to adapt to their new environment.

While a clownfish is a symbiotic creature, typically sharing a host relationship with an anemone in the ocean, they can still survive in an aquarium; however, their behavior when living in an aquarium may seem odd to the unsuspecting onlooker.

It is common to find clownfish kept in aquariums sleeping at the surface of the tank, often appearing to float on their side. Many clownfish will adopt a specific area at the top of the tank as their home and will spend the majority of their time swimming or floating there.

If you are interested in adding a clownfish to your aquarium as a new member of your fish family, here are some fun facts that will help you know what to expect along the way.

How to identify the best clownfish to add to your aquarium?

Five fun facts about clownfish.

While it isn’t concerning that your clownfish swim at the top of the tank, keeping your tank clean and well filtered is essential to their survival. The temperature of the water must be maintained at 74-79 degrees Fahrenheit, with a pH between 8 and 8.4 to keep them healthy.

When choosing a clownfish, it is important to know they can be aggressive towards other clownfish species, so you’ll need to only have one species living in the same aquarium. It is also important to consider the size of the clownfish you pick to ensure your tank is large enough for them to thrive.

Here are some other facts to consider when you add clownfish to your aquarium.

Clownfish and Sea Anemones Share a Symbiotic Relationship

In their natural habitat, the ocean, clownfish are drawn to anemones. Anemones are predatory by nature; however, clown fish use this to their advantage. Immune to the anemone’s sting, the clownfish will live within the tentacles of the anemone, providing it with shelter and protection from its predators.

The anemone also feeds the clownfish as the clownfish benefits from the leftovers of the anemone’s meals. In turn, the clownfish does their part by defending its anemone host from its predators or parasites.

While clownfish in the wild are almost always found near their anemone, they do not need one to survive in your aquarium. Without the threats of their enemies in the ocean, the clownfish does not need the anemone to defend them from its predators. And since you’ll be supplying food for your clownfish, they won’t need to feed on the anemone’s scraps.

There are Many Species of Clownfish

Currently, there are 30 known species of clownfish. Among them are the Tomato Clownfish, Maroon Clownfish, and the Common Clownfish everyone loves thanks to Disney’s “Finding Nemo.”

Oddly enough, while the Common Clownfish may be the most popular, and are relatively easy to care for, the Clarkii clownfish may be your best selection if you’re just getting your toes wet with these fish. The Clarkii are inexpensive and stout. They are not very aggressive, and according to, they are perfect for “the saltwater aquarist with a medium sized tank!”

Here are a few of the easiest clownfish species to care for:

  • Common Clownfish
  • Cinnamon Clownfish
  • Tomato Clownfish
  • Maroon Clownfish
  • Clarkii Clownfish
  • Saddleback Clownfish

Not All Clownfish are Orange

When you hear clownfish, you probably picture an adorable orange fish with white stripes, but not all clownfish are orange. In fact, if you put together several species of clownfish, your aquarium will look like a swimming rainbow. A number of different species of clownfish are identified by their unique coloring.

Some of the most beautifully colored clownfish include the black storm clownfish, Saddleback clownfish, and Pink Anemonefish. The Saddleback Clownfish from the Pacific Ocean is often dark brown in color with white stripes and a few yellow highlights. And just as its name suggests, the Pink Anemonefish is a pinkish hue and with one thin white stripe near its head.

Clownfish Follow a Hierarchy of Dominance

In a group of clownfish, each member has a ranking, and the dominant member at the top of the group is always the largest, most aggressive female amongst them. How do they sustain this hierarchy if the female dominant dies? The next male clownfish in line transforms into a female and takes over as leader of the group.

Yes, clownfish are hermaphrodites. Each is born male and later has the ability to transform into female once they have matured. If the clownfish are part of a group, living in the same sea anemone, then only the dominant female and highest ranking male within a group mate together for reproduction.

Male Clownfish are Romantics

Males who are ready to spawn make preparations ahead of seeking out a female. The male will set up a nest, perfect for watching over and protecting a female’s eggs before finding a female to spawn with. Once the nest is ready, the male clownfish courts a female to attract her by extending his fins, biting, or chasing her according to

Once the female lays the eggs and the male fertilizes them, the male clownfish is the one who cares for them. He keeps the eggs protected by hiding them from dangers with his fins. The male will also eliminate any unfertilized eggs or eggs tainted by fungus by eating them; however, once the eggs hatch, his responsibility ends.


While a clownfish may act odd in your aquarium, it does not mean they aren’t a great addition to your salt-water fish family. These fish come in a variety of colors, shapes, and sizes and can add beauty and life to your aquarium. When choosing which clownfish to add to your aquarium, don’t forget to look at the many species outside the common clownfish, and find the one that best suits you and the other fish in your aquarium.

And remember, if your clownfish is swimming at the top of the tank, that’s okay. It’s just their way of making a home in your home!