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How To Stop Zoanthids Melting!

If you are trying to keep corals but you find that you cannot get zoanthids (sometimes known as zoas) to thrive in your tank, you might be feeling a bit puzzled about what’s going wrong.

Many people have issues with zoanthids melting, apparently for no reason whatsoever, and it’s a frustrating and confusing problem that you might spend a lot of time and energy trying to fix.

Don’t be too disheartened if you are having constant difficulty with this, because it is very normal, and a lot of people struggle.

Zoanthids are very popular corals, and they come in a whole range of different colors and formations, so you should be able to easily find one that suits your tank.

However, you also need to make sure that your tank suits the coral, and this can be challenging, especially if you are relatively new to keeping coral and you have only recently set up your tank.

Zoanthids can be incompatible with many different things, and this may cause issues when you are trying to keep them.

If you keep losing zoanthids, you should not just keep trying without making amendments to the tank conditions and the water quality.

Test kits, inspections of the other corals and the livestock you are keeping, and careful observation will be necessary, or you will probably find that the problem persists.

What Causes Zoanthids To Melt?

Many different things can cause zoanthids to melt, and there seems to be a great deal of uncertainty about the issue, with water quality, incompatible coral species, fish damage, light levels, nutrient levels, and many other factors playing into the health of your zoanthids, and helping to determine whether the corals survive well or not.

If you find that zoanthids are constantly melting in your tank, you will need to look at each of these things to try and identify the cause.

Fish damage is probably one of the commonest problems, and may be the easiest to spot; check whether any of your fish are nibbling or attacking the corals, and try watching the tank at different times of day to check on the various species.

If a fish is responsible, you will need to move the fish out of the tank, so check both during the day and at night with a flashlight. You could also check for damage on the zoanthids, but this can be tricky to spot sometimes.

If you don’t think fish are the issue, you should do a water test and make sure that the levels are correct, and check whether the zoanthids are getting more light than they can handle.

You should also make sure none of the corals they are kept with are incompatible with them, and ensure that the zoanthids are getting enough nutrients, as they are quite heavy feeders.

“Armor of God Zoanthid” by la.kien is licensed under CC BY 2.0. To view a copy of this license, visit

How To Stop Zoanthids Melting!

You can only stop zoanthids melting by determining the cause of the issue, so start by assessing the tank and the conditions that they are being kept in.

You may find that reducing the amount of light that the corals are getting will help, or you might find that moving them into another part of the tank stops them from melting.

Try feeding them, and don’t keep the tank too clean; zoanthids are heavy feeders and they like a little bit of dirt to keep the nutrient levels in the water high.

If you find that fish are eating the zoanthids, you will obviously need to relocate the fish to another tank, or they will destroy your corals; there is no way to stop fish that have decided to nibble on your zoanthids without removing them entirely, so be prompt about this, because they can do surprising amounts of damage in very little time.

Similarly, if you discover that one of your corals is incompatible, you will either need to relocate that species or the zoanthids.

Look out for nudibranchs and other predatory species hiding among the zoanthids, as these can disguise themselves extremely well and could do great damage without being noticed.

It’s important to note that even if you have fixed something in the tank, it can take time for corals to recover, so you may not see an improvement in your zoanthids immediately. Allow them a few weeks to recover.

How To Stop Your Zoanthids Melting In The Future!

Prevention is often better than cure, so it’s a good idea to keep an eye on your tank parameters at all times, and to ensure that there is plenty of food for the zoanthids.

Do regular water tests to check that the quality is high enough, and feed the corals frequently to keep the nutrient levels up. You can spot feed them if you prefer, but they do need plenty of food to survive.

You can stop your zoanthids from melting by finding the optimum position for them in your tank setup; this may be in one of the darker corners, as too much light can be problematic for them.

Select a shaded spot, especially if you have bright lights or lights that cannot be adjusted. 

You should also ensure that you are only keeping compatible species, and look out for predatory fish that might be nibbling on your zoanthids.

Check both the corals and the fish in the tank, as both of these can cause unhappiness and make your zoanthids melt away to nothing. Always check the compatibility of a species before you add it to your aquarium.


Zoanthids melting is an extremely frustrating problem to encounter, and it can be very hard to tell what is causing it, because there are so many potential issues that can crop up within a tank, and it may be a combination of problems. You should start by checking whether there are any fish or corals that may be causing the issue, and either relocate the zoanthids or the fish if so. Once you have done this, start checking the tank suitability, including the nutrient levels, the light levels, and the water quality.