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6 Common Digitate Hydroid Jellyfish Questions Answered!

The number of people within the fish keeping community that are having problems with digitate hydroid jellyfish and other types of hydroid is constantly increasing with hydroid jellyfish being a common problem for many people.

Although it is common to think that only people new to fish keeping have issues with pests like hydroid jellyfish, people of all levels of experience within the fish keeping community can end up accidentally introducing hydroid jellyfish to their tanks and having problems.

This is why we see a large number of people reaching out every single month with questions about hydroid jellyfish to try and understand them better in the hope that they will be able to better defend their tanks against these little critters.

We do see a large range of questions being asked each month but the majority of the questions tend to fall somewhere in one of the categories that we will be covering in this article.

We truly hope that we will be able to help our readers better understand why they are having problems with hydroid jellyfish and how they are able to get rid of them.

Our table of contents below should make it as quick and easy as possible for you to navigate the article and skip to specific sections that you need information for but if you are having a repeating problem with hydroid jellyfish in your aquarium then skimming the full article will probably be worth it.

What Is A Hydroid Jellyfish?

The term hydroid jellyfish is used to describe a number of slightly different star-like microorganisms that can quickly develop in an aquarium.

Their appearance is generally a tiny white star but there are some types of hydroid jellyfish that do look a little different.

In addition to being known as hydroid jellyfish, these little critters are also known as Cladonema, Hydromedusae & fixed Jellyfish in some areas but they are usually referred to as hydroid jellyfish.

Are Hydroid Jellyfish Poisonous?

Hydroid jellyfish are tiny jellyfish and they do have a sting that can be poisonous to some lifeforms.

It is very rare that a human will have problems with their sting but the fish or corals in your tank can end up having problems due to being stung multiple times per day if you have a large number of hydroid jellyfish in your tank.

Unlike similar creatures, hydroid jellyfish are poisonous and can sting in both the polyp stage and the medusa stage so removing them from your tank as early as possible is recommended.

Are Hydroids Jellyfish Bad In A Reef Tank?

Hydroid jellyfish are not considered to be reef safe as they are able to sting your fish, coral, and anemone in your tank with these stings being strong enough to cause serious problems in some of the more sensitive fish and corals.

Due to the reproduction rate of hydroid jellyfish, they can rapidly take over an aquarium too leaving no safe spaces for your fish to avoid their stings too.

What Do Hydroid Jellyfish Eat?

Hydroid jellyfish in both the polyps and medusae stage will feed on pretty much anything they are able to find in your tank ranging from tiny plankton and microscopic plants to your fish that they are able to attach to and everything in between.

With hydroid jellyfish being able to rapidly reproduce, they are able to take a huge amount of plankton from the water in your tank and potential cause problems in your ecosystem due to there not being enough food the other organisms in the tank.

Where Do Hydroid Jellyfish Come From?

Hydroid jellyfish are usually added to an aquarium by accident with the hydroid jellyfish being on new substrate, rocks, plants or even fish that you add to your aquarium.

This is why we always recommend that you do your best to quarantine any potential new addition to your aquarium for as long as possible to make sure it is free from all possible contaminants.

Hydroid jellyfish also reproduce at a rapid pace too and will quickly cause issues in your tank even if you accidentally add a small number of them.

How Do You Get Rid Of Hydroid Jellyfish?

Very few things actually eat hydroid jellyfish so the best way to remove them is to manually scrape the tank as soon as you notice that you have a hydroid jellyfish breakout.

They tend to congregate on live rock making it a little easier to get rid of the bulk of them but even a small number of remaining hydroid jellyfish in the tank can quickly swell their populations again.

Although some people claim that their peppermint shrimp have eaten hydroid jellyfish in their tank, there are plenty of contradicting reports to suggest that peppermint shrimp are not an effective way to get rid of hydroid jellyfish.


That brings our article going over hydroid jellyfish to an end. We hope that we have been able to help our readers better understand hydroid jellyfish, where they come from, what they eat, and how to get rid of them. We understand the frustration of our readers who are having problems with hydroid jellyfish as they really can be a pain to deal with but with time and persistences, you can remove them all from your tank with minimal damage to its ecosystem.