Brown Jelly Disease: Cause and Treatment

If you own a saltwater aquarium and you notice a brown substance similar to jelly covering the surface of your coral, this is absolutely not something you should ignore. This brown stuff is an indication that your coral has a brown jelly disease, a serious condition that can easily kill your coral if left untreated.

Today, we’ll be going over everything you should know about brown jelly disease, including what causes it, how to treat it, and more. 

What Causes This Disease?

Unfortunately, it’s not very well known what specifically causes brown jelly disease. The jelly itself usually consists of multiple substances, which often include bacteria, protozoans, and dead or dying coral tissue.

However, some research suggests a close link between this disease and the presence of a protozoan known as Helicostoma nonatum. Analyzing the jelly produced by this disease always reveals the presence of high levels of this protozoan.

Despite this, it is unclear exactly what role this protozoan plays in the disease. It may indeed be the primary cause of the disease, or it may be a secondary organism that is attracted to infected coral tissue.

In truth, brown jelly isn’t really a disease in and of itself, but a symptom of an underlying condition. It may be the result of an infected injury your coral has sustained, it may be a bacterial infection that your coral just happened to pick up, or it may be because your coral is in a stressful environment.

In any case, if you notice the signs of brown jelly in your coral, it’s important to treat it accordingly as soon as you can; it may have serious consequences for your coral otherwise.

How Concerned Should I Be About This Disease?

If you see the signs of brown jelly occurring in your coral, you should definitely be concerned. In most cases, brown jelly is extremely fatal to coral; it can kill an infected coral within a few days to a few weeks.

Additionally, the brown jelly disease can potentially spread to other corals within your aquarium if you don’t treat it in time. In general, most healthy corals should be able to resist being infected by this disease, but if you have other injured corals in your aquarium then they might be susceptible to infection.

How to Deal With Brown Jelly Disease

Brown jelly is, unfortunately, often very difficult to treat; corals that are affected by this disease often do not survive.

However, that’s not to suggest that all hope is lost if your coral does catch a case of this disease. There are indeed some treatment methods available that can potentially be effective. In this section, we’ll go over some of the treatment methods that you may want to try.

Increase Your Aquarium’s Water Flow

If you can, increasing the water flow within your aquarium can be a cheap and easy way to deal with a case of brown jelly. However, this method of treatment will be more likely to work if your coral only has a small, localized case of this disease.

Increasing your aquarium’s water flow allows your coral to take in more oxygen and nutrients, which are obviously beneficial to your coral’s overall health. It also makes the water in your aquarium less stagnant, which can prevent the brown jelly from accumulating on your coral.

Frag Your Coral

“Fragging” your coral refers to cutting off part of your coral; the term is short for “fragmenting”. If your coral is affected by brown jelly disease, you may have to frag the infected parts of your coral if you want your coral plant as a whole to survive.

While you may be hesitant to frag your coral, it’s often necessary if your coral has a severe case of brown jelly. 

When fragging your coral, it’s a good idea to use a turkey baster to suck up any excess fragments of brown jelly floating around beforehand. You should also temporarily disable your aquarium’s water flow, to prevent any brown jelly from finding its way to your other corals while you remove the infected bits.

Try an Iodine Dip

Iodine dip can be an effective method for treating a variety of coral-based illnesses. Below, we’ll outline all the steps necessary to correctly treat your coral with iodine:

  1. Get yourself some iodine. If you can find a bottle of Lugol’s iodine, that’s generally the best type of iodine for coral.
  2. Get a container that can hold the piece of coral you want to treat. A plastic serving saver is fine for this purpose.
  3. Fill this container all the way with water from your aquarium.
  4. Add some iodine to the water. Add enough so that the water is mostly opaque. Stir this mixture well.
  5. Place the container in a larger tub with a heater to keep the water at the proper temperature. Alternatively, you can place the container into your aquarium and clamp it to the edge to prevent it from spilling.
  6. Dip your coral in the iodine solution for about 10 to 30 minutes, depending on the severity of the infection.
  7. Once your coral has been dipped, you can place it directly back into its original tank; there’s no need to rinse it off beforehand.

Use a UV Light

A UV light won’t do much to treat coral that has already been infected by brown jelly disease, but it may help to prevent your coral from catching it in the first place.

UV light kills bacteria and other pathogens, and it may help to reduce the risk of your coral coming in contact with whatever organisms cause brown jelly. However, bear in mind that UV light isn’t an infallible means of protection against coral disease. 


Brown jelly is an insidious and dangerous disease that many types of coral can catch. If your coral does come down with a case of this disease, it’s imperative that you deal with it at once, lest you want the coral population in your aquarium to be ruined.

Luckily, there are several ways you can deal with this disease should it occur. If you act quickly and know what you’re doing, there’s a good chance you’ll be able to save the majority of your coral. 


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