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Will Clownfish Host Hammer Coral in a Saltwater Aquarium?

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Colorful, saltwater-dwelling clownfish survive in their native ocean environment by sheltering with a protective host, usually an anemone but also corals. In this symbiotic relationship, the host protects the clownfish by stinging approaching predators. The clownfish provide nutrients for the host and clean the host of algae and the waste products of other fish. 

Saltwater aquariums provide predator-free environments for clownfish, but clownfish will host hammer coral in a saltwater aquarium. The instinct to host a protective anemone or coral is hereditary. Even aquarium-bred clownfish that have never known the ocean environment seek a protective host. 

While clownfish will host hammer coral in a saltwater aquarium, problems can arise in the hosting relationship. Read on to learn about the issues that can develop and how to resolve them. 

Encouraging Clownfish to Host Hammer Coral

If you have a small aquarium or your aquarium lacks sufficient lighting, you might not be able to add an anemone to your tank. If you have younger children, you may not want to take a chance on including an anemone.

Unlike corals, anemones move. You can find them anywhere in your aquarium, including blocking the water flow, causing an overflow, or in a place that’s so difficult to reach that you get stung in return for your rescue efforts. Anemones aren’t necessarily grateful.

Most anemones aren’t harmful to humans. However, the National Center for Biotechnology Information (NCBI) identifies the venom from Stichodactyla haddoni, Haddon’s Saddle Carpet Anemone, as one causing severe injuries to humans. The information appears in Table 1. 

Haddon’s Saddle Carpet Anemone is one of four anemones listed by as potential clownfish hosts for those seeking to recreate a natural reef setting in their aquariums. 

The upside is that the NCBI report is that the venom may have therapeutic uses. 

Again according to, another reason not to use anemones in an aquarium is that they grow slowly and are difficult to keep healthy. 

For that reason, most anemones are collected from the wild, which harms the world’s reefs. identifies Entacmaea quadricolor, the Bubble-Tip or Rose Anemone, as an exception. 

This anemone actively splits to create new clones. By comparison to other anemones, it also grows quickly.

All of these are good reasons to encourage your clownfish to host a coral.

BTW: make sure to check out my list of anemones and corals that are suitable for clownfish. You can find it right here on my website.

Suggestions for Encouraging Clownfish to Host Hammer Coral

If an anemone isn’t available, clownfish will host hammer coral. Clownfish have strong little minds of their own, though. So, you may need to strengthen your patience. 

One important factor is to offer your clownfish a hammer coral that is large enough for them to host. The hammer coral should be larger than the clownfish so that they can swim inside it. has suggestions for encouraging clownfish to host an anemone that should work with hammer coral equally well.

  • Put your hammer coral in the aquarium first. Let the hammer coral establish itself. 
  • If the clownfish is already in the aquarium, move it to another tank temporarily.
  • Get a clear, plastic tube with plenty of room for your clownfish. 
  • Place one end of the tube nearly touching the hammer coral.
  • Put your clownfish in the tube and let it swim through to find the coral.
  • Use a net or a scraper to guide the clownfish toward the coral. 
  • If the clownfish still ignores the coral, monitor the relationship for a few weeks.
  • Again try guiding the clownfish toward the coral with a net or scraper, or use the tube to reintroduce the clownfish to the coral.
  • Start again with an aquarium that contains only the hammer coral and the clownfish. Repeat the steps above. 

Another idea to try if your clownfish continues to resist hosting the hammer coral. Move the hammer coral to an area of the aquarium where the clownfish spend a lot of time. 

Make sure, though, that it’s an area where the coral receives the right amount of light and water flow. 

If you have a breeding pair of clownfish that resist hosting the hammer coral, move the coral close to where the two clownfish have their clutch of eggs. 

Again, make sure that the coral has the light and water flow that it needs.

Clownfish Hosting Behavior

You may see your clownfish engaging in some unusual interactions with your hammer coral before they host it. For the clownfish, it means that they’re preparing to host the coral. 

The hammer coral, on the other hand, may find the behavior too aggressive and withdraw. 

According to, some species of clownfish may produce mucus that covers their scales and protects them from the stings of anemones and corals. 

However, all clownfish also prepare by taking additional steps to protect themselves from the stings. 

You may see your clownfish rubbing repeatedly and frequently against the hammer coral or slapping it with their tails. They do this to cover themselves with the protective mucus coating produced by the hammer coral.

Your clownfish might also take the tips of the hammer coral’s polyps in their mouths. They might swim around with an open or drooping mouth for a while after that. The clownfish might be allowing themselves to be stung to build up their resistance to the toxin in the coral’s sting.

Signs of Hosting Issues

While anemones are hereditarily suited to hosting clownfish, corals are not. Hammer corals have no genetic expectations of having colorful little fish rubbing against them or nibbling at polyps. 

If your hammer coral finds that your clownfish are too aggressive, it may withdraw or close itself up. If it does this, it won’t be collecting food from the water flow, and it may not be getting enough light. Monitor the health of the hammer coral, but be patient for a while.

When the hammer coral retreats, the clownfish may retreat as well. The coral may then extend itself again. The clownfish may return when the coral re-emerges. The two may go through a few rounds until the coral tolerates the clownfish. The clownfish could become gentler, too. 

If the health of the hammer coral becomes imperiled, Remove it, and give it time to recover. 

You can use the steps above to introduce another hammer coral or a different coral to your clownfish, or you can wait until your coral recovers and try again. 

Final Thoughts

Hosting is a hereditary behavior for clownfish. And, clownfish do accept substitute hosts in place of anemones. However, it’s not an inborn behavior for a hammer coral to accept a hosting clownfish. Your hammer coral may withdraw if your clownfish is too aggressive. 

You may need to exercise patience and let the relationship between your clownfish and your hammer coral develop slowly over a few weeks. The relationship may not go swimmingly for a while. Monitor the health of the hammer coral, but give the two a few weeks. 

The chances are that eventually, your hammer coral will accept your clownfish, and you’ll find your clownfish happily hosting in its new home. 


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