Why Would A Clownfish Swim At The Top Of The Tank?


It could be very disturbing to you when you find your Clownfish swimming at the top after you brought him home from your favorite petstore. Many fishkeepers have observed this same behavior in their Clownfish, but is it serious?

All Clownfish, when introduced to a new tank, they usually swim at the top for a couple of weeks and you could see problem goes away itself. If the problem persists, notice if there is a lack of Oxygen in the water, since your Clownfish is gasping for more air at the top, which indicates a potential for parasitic disease. Check the water temperature is not higher than 78 deg. F.

No matter where your Clownfish likes to stay, it should approach you during feeding time to take its meal before it goes back to the top of the tank.  The fact that it eats to satisfaction is an indicator of good health.

As long as, your Clownfish is eating properly and not gasping for air, there’s nothing to worry about.  The behavior should correct itself in a couple of weeks. 

For its safety, make sure your tank has a lid so your Clownfish won’t jump out and kill itself.  Even juvenile Clownfish have strong enough muscles to accomplish this.

Clownfish Gasping For Air?

Now if your Clownfish has lost its appetite and is breathing rapidly, you should be looking at the possibility of disease.

If your Clownfish is having shallow, difficult breaths, it can be poor water quality or it can be parasites like flukes, Brooklynella, velvet, or ick.  Those parasites attack the gills.

Test your saltwater tank for ammonia and copper right away and make a partial water change.  Then test your water again.

Clownfish Swim At The Top Of The Tank
Clownfish Swim At The Top Of The Tank

A refractometer is a good alternative to a hydrometer.  This instrument gives a pretty good salinity measure.

Correct all water levels and observe your Clownfish.  Also look for disease symptoms such as swollen gills (Brooklynella), white spots (ick), flashing or scratching on surfaces (flukes), or head twitching and gold-brown dust (velvet).

If you are interested in learning more about your fish behavior, check out the links below:

How Do You Treat Clownfish?

There are several treatment options for mild to severe Clownfish parasitic diseases.

Immediate relief can be given through a freshwater dip.

Will A Freshwater Dip Kill Marine Ich?

A freshwater dip will not kill all marine ick, flukes, lice, or other parasites but the change in water will make some of them drop of the skin of your Clownfish, giving it momentary relief from some itch.  The dip is given as a first aid measure for very irritable fish.

You will still need medication especially for severe cases of parasite infections.

How to freshwater dip Clownfish?

  • Fill a thick plastic bag with a gallon of dechlorinated or RO DI water and acclimate it to the tank so that the temperature will be the same.
  • When the temperature is right, pour it into a bowl or container and put the Clownfish in.
  • You don’t want the fish not moving or laying on its side.  If it starts doing that, tickle the tail a bit or agitate the water so it will swim.
  • You should be able to see the parasites falling off like wet dust, fingernail, or clear shadow dropping to the bottom of your bowl.  Keep your Clownfish in the dip for 1 to 3 minutes depending on the severity of the disease and the tolerance of your fish.
  • Return your fish to the hospital tank.  If you used a net, rinse and dry it thoroughly to avoid re-infecting the tank.
  • If your Clownfish isn’t swimming in the saltwater, continue to tickle its tail to move forward until it has expelled all the freshwater out of its gills.

Freshwater dips are also useful for keeping minor cuts and lacerations from getting infected.

How Do You Treat Internal Parasites In Fish?

Copper and formaldehyde (formaline)-based dips are still the best ways to completely treat Clownfish parasites.  Get a hold of a recommended formula from a pet store and follow the instructions carefully, making sure you Clownfish is able to tolerate it.

These chemicals are pretty strong so make sure you don’t overdose the hospital tank water.

To avoid parasites in the future, don’t forget to quarantine any new fish regardless of how trustworthy their sources are.

Is 80 Degrees Too Hot For Reef Tank?

Your Clownfish might have come from a not-too-warm tank in the pet store, or your weather might have turned summery and your water is being influenced by it.

The tolerance for heat is different from fish to fish.  Your Clownfish might be suffering from thermal stress with water that’s too warm.  If your temperature is up to 80 deg F, you might want to lower it a couple of degrees and see if it makes any difference to the Clownfish’s behavior.

But beware of lowering your temperature too much.  Try and keep it between 75 and 78 deg F, although 72 is still tolerable.  Anything lower than that and there might be a slight loss of appetite.  Juveniles Clownfish may experience stunted growth in constantly cold water.

Do Clownfish Like High Flow?

No.  Clownfish find it a bit difficult to swim in water with high flow so they mainly avoid it.  They would rather stay at a certain spot in the aquarium where the water is calmer.

Clownfish in fish tank
Do Clownfish like High Flow?

It certainly is possible that your Clownfish doesn’t like the heavy flow of water down below, and chooses to avoid it by staying on top.

Why Does My Clownfish Stay In One Spot?

If your Clownfish is not sick or wounded, is eating healthy, and is responding well to you, then you need not do anything drastic.

Clownfish are weird that way.  They stay in one spot for weeks (or they might often go back to it) without a plausible cause.  If they pick a corner of the tank, they might be “hosting” that space.

There are instances when a Clownfish is new to a tank and might not feel that comfortable yet so it stays at the top with its back out of the water. 

Try to give them a new sleeping spot in the tank, some of them choose to go to Anemone right away but some will not take any notice. Fishkeepers have reported seeing this odd behavior. After a couple of weeks, their pets finally moved to another spot in the lower part of the water column even without intervention.

What Is Clownfish Hosting?

If you think your Clownfish is hosting a space, it might be a sign of insecurity.  Make sure your reef tank has lots of corals and décor (if not an anemone) it can bond with and host.  

You can also try a pot, a wide-mouthed PVC tube (make sure the edges are not sharp), or even a plastic anemone for the purpose.

Clownfish and anemones have a symbiotic relationship where the anemones protect the Clownfish from predators through their toxic sting, and Clownfish feed the anemones with its feces and food.  This relationship is what we call Clownfish hosting.

This is also the reason why Clownfish are also called anemonefish.

Clownfish poop contain nutritional nitrogen which the anemone eats. 

Because it is ingrained in them even if they’re captive-bred, Clownfish have that natural instinct to host something.

What Is An Anemone?

An anemone, or rightfully a sea anemone, is a flower-like sea creature with a ring of long-stinging tentacles that help it capture food.

Clownfish
Clownfish in Anemones

It’s named after the land flower with a colorful appearance, so don’t confuse the two.

Between that ring of tentacles is its mouth, which it feeds with zooplankton, clams, shrimp, mussels, and such.

Can Anemone Kill Clownfish?

Because anemones have toxic tentacles, most sea creatures avoid it.

However, Clownfish are heavily covered with a thick layer of fish mucus, so it is able to tolerate the toxins of some varieties of sea anemones.

This is beneficial to Clownfish as they are awkward swimmers and would be heavily subject to predation if not protected by an anemone.

But not all anemones are kind to the Clownfish.  Of the over 1000 species of sea anemones, Clownfish can only host about 10, the most common being the Bubble Tip.

Most saltwater reefers only keep 1 anemone in their tank, if any.  Multiple Clownfish will share.

Can Clownfish Live Without Anemone?

An anemone is not necessary for a Clownfish to thrive.  There is also no guarantee that the Clownfish will take to the anemone once you get it in the tank.

Many saltwater fishkeepers discourage it since Clownfish may already feel safe in a tank and might not need a real anemone to defend it.  It isn’t really a necessity.  And for a not-so-experienced hobbyist, having an anemone is added work to the reef.  You should have an alternative, though, to make sure your Clownfish feels secure.

Will Clownfish Host Fake Anemone?

Because Clownfish are wired to host, they will even take to hosting a silicone anemone. 

You can even buy those glow-in-the-dark plastic anemones to make the Clownfish think they’re really under the sea.

What Corals Do Clownfish Host?

Other than anemones, Clownfish can also host different kinds of easy-to-care-for corals such as Duncans, Elegance, Favias, Hammer, or Torch.

Clownfish will host any type of coral they fancy, whether soft or hard.

Clownfish may also host other things, such as a Feather Duster (or fan worm), which is a curious-looking worm with feather-like tentacles. 

They may even host things like your filter or heater!  But no matter what it is, the important thing is that they don’t stay at the top of the tank anymore. We told you they were odd, didn’t we?  Enjoy your funny Clownfish

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