These Corals Need Warning Labels

The day you add corals to your saltwater aquarium is the day two things happen:

#1: You become a reef enthusiast

#2: You have to have more coral, and more coral, and more coral…

In your quest to fill every inch of your tank with coral, many varieties are often picked as “beginner corals”. However, they can overgrow or kill other corals, as well as flat out become a pain in the ass. Since these corals don’t come with warning labels, I’m giving them ones of my own:


Quickly becomes a nuisance as it grows quickly and pops up in different places all over your tank. Yes, you can try to control it by trimming it every 2 weeks, but do you really want another lawn to mow?

Warning label: Best left out of your tank.

Green Star Polyp

I’ll admit, it looks cool as it moves in the water flow of your tank. However, it grows quickly and will kill anything it touches (including SPS). The exception is mushrooms.

Isolation GSP

GSP Isolated

Warning label: Place this coral in solitary confinement by putting it on a piece of rock that is placed away from other rock. As it grows off the rock, you can trim it back.


A great starter coral as you can’t kill them. Seriously, you can’t kill them. When I first started with coral, a fellow reef keeper left some in a ziploc bag in my mailbox for several hours in the 40 degree cold. They lived through it, no sweat.

You can remove them by cutting them with a razor blade, but unless you epoxy over the base, they’ll come back.

Mushrooms also pop off rocks and will drift around your tank until they find a place to latch on. If they latch on to a rock in a place where you can’t get to them easily, they’ll soon grow and take over.

Warning label: Unless you want a soft coral-focused tank, do not put them in your tank.


Rhizos aren’t so much a beginner coral, but they are very popular right now so I have to mention them.

Rhizos eat fish. Healthy fish. Yes they look cool, but so do your fish.

Warning label: This coral has been known to eat healthy, happy fish. Keep with caution.

Teal Palys

Another soft coral that grows very quickly and will overgrow other coral. They will also pop off rocks and drift around your tank till they latch onto something – then they’ll start taking over…again.

Tal Palys

Teal Palys on the Move

Warning label: Best left out of your tank.

Torch and Hammer Coral

Another fun coral to watch as its tentacles sweep in the current. However, at night, they throw out sweeper tentacles that can sting and kill any corals close to them.

Warning label: Place 5″ or more away from other corals. Unless, of course, you want to kill the other coral.

Keeping corals opens up a whole new experience when keeping a saltwater tank, and they are well worth the cost. Note the above warning labels and you will save yourself a lot of disappointment and headaches.

What coral mishaps have you made?

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Comments for this article (28)

  • Cameron Turner says:

    Excellent warnings Mark!

    Mushrooms and Hammer’s were on my “acquisitions” list.

    Perhaps you can suggest a list of excellent corals to keep? Not a list of “the best” as it’s probably very subjective, but a set of corals that are hardy, colorful, docile, interesting etc…

    Would make a good shopping list for us budding reef enthusiasts.

  • Cam-
    The mushrooms I would avoid, the Hammer would make a nice addition – just give it some spacing between it and other corals.

    I’d be happy to make a list of corals I recommend. I’ve added it to my list!

  • Steve says:

    I got Xenia for my tank. It grew really well and I was able to sell frags to friends and to my local fish store. I was able to cover the cost of salt for a year and obtain other corals and fish. Had I known I could have planned started off with just Xenia in my tank and then use the proceeds to build up the rest of my collection! After 6 months it then mysteriously disappeared, never to return.

    My mushrooms though are doing really well. They started from one single mushroom, and now I must have over a hundred. They glow a nice flourescent green under actinics. I decided at the outset that I was a reef enthusiast and to buy equipment etc. that would suit soft corals as I didn’t want the expense or have the time for the upkeep of SPS etc. so am happy with them in my tank.

    I am beginning to wonder though about cutting them back to accommodate more LPS, so am concerned about your comment about not ever being able to get rid of them. In the UK there is a shop selling the same mushrooms as mine for $15 each! Perhaps I just start selling them myself like I did with the Xenia!

  • Liz says:

    I started my 125g tank a bit over a year ago with a small rock of mushrooms knowing I wanted to focus of sorties & LPS. I don’t find the majority of SPS corals attractive. I have a huge colony of pulsing pom- pom Xenia. It’s gorgeous and the motion draws every visitor to my house into a mesmerized state of wonder. I trim it every couple months (not weeks! And I have a very healthy tank) and it’s quick and easy.

    I also have galaxia, another aggressive sweeper tentacle coral. Haven’t had any issues with it. When it was small I gave it room. It’d grown (a lot!!) Out next to leathers, candy canes and frog spawn and all is well.

    Teal palys I’ll agree with being crazy fast growers and invasive. Good for covering things quick but ya gotta watch them.

    The only coral caused death in my tank isn’t on your list. I had encrusting gorgonian outgrown its rock and sting a plate coral and kill it.

    Another I don’t see on your list is anthelia. I have it and love it for its size and motion, but it grows insanely fast. Far faster and bigger than Xenia. It is very easy to trim and remove.

    I love the softies and in my big tank at a year I have some gorgeous mature colonies that are vibrant and so pretty swaying in the current. They do grow faster than my LPS or SPS but I haven’t found them to be a problem.

  • Kevin says:

    Pom Pom xenia doesnt spread as fast as the silver tip variety, but I agree with Mark, I wll never put it in my tanks again.

  • Marc M says:

    That is the main reason why I am no longer a reefer. I must have lost nearly $500.00 in corals due to these problems so thats why I went FOWLR, Thats Fish Only with Liverock. I am much happier and have been very fortuante in obtaining a christmas emperor angel as well as a clarion. They are in a 500 gallon tank and haven’t been attracted to corals ever since. Large angels and surgeons are so much more fun to me anyways. Hey Mark, why don’t you start some vids on some FOWLR tanks in the future, would love to see that.


  • Steve…holy cow! You can sell Xenia over there?! Here in Texas you can’t give the stuff away.

    If you want to get rid of the shrooms, the only 100% effective way to do it is to take the rock out that they are on. You can breakup the rock with a flat head screw driver and hammer and sell smaller bits of rock with mushrooms on them.

    Go for it and let me know how it goes!

  • Liz…thanks for the reminder about the anthelia. I forgot about that one.

    Did you mean goniopora? That is a very aggressive coral that will nuke pretty much anything it touches. Good thing it grows very slow for most people.

  • Marc…nice! post a pic for us to see!

    I’ll look around for FOWLR tanks. Here in central TX they are very few. Thanks for the idea

  • John says:


    I agree with your list and I’m glad you made it. What annoys me is two things:

    1. That some local fish stores will prey on customers and sell them anything. I stopped a guy new to the hobby from buying sea horses. The guy at the store didn’t even ask him his skill level. It’s crazy.

    2. Why are people buying living creatures without the smallest bit of research. I have both the Pom Pom xenia and hammer, but I read everything I could about them before I bought them.

  • John…some businesses are only concerned with making $$$, not doing what’s right for the customers. These businesses do not understand the value of a long term customer. I agree with you, it’s sad and I wish it would stop.

    As far as research, most people impulse buy so why do research when you can BUY! BUY! BUY! I’m working on classifying corals based on tank personality so we’ll have to spread that around to help mitigate against uninformed purchases.

  • Steve says:

    A list of recommended corals based on tank personality would be really helpful.

  • Chris Whitney says:

    Looking forward to a list for enthusiast, will check to see how many mistakes I have made. I do love my hairy mushrooms as a stater “I cant kill it critter”. Also have a small strip of stars so will think about moving them away, but they do add nice life to the tank. The stars were given to me free! Figures…

  • I can’t think about how many times people gave me GSP or mushrooms when I started keeping coral. I’m sure I left their house giddy as a kid in a candy store and the person giving me the coral was just laughing.

  • ScottA says:

    I’m setting up a new 210 gallon reef! Upgrading from my 30 gallon I have maintained for 4 years now. I’m glad I made all these coral mistakes before buying this new tank!!

    I’m going to keep the 30 going so I can keep enjoying these corals. Without having to stress about the fact that they are taking over. (I don’t really care, that’s what the tank is for…

  • Ryan says:

    Hey Mark have you made that list of recommended corals? I was searching around for it but did not come across it.

  • Brian Davis says:

    Haha! Ryan I was just wondering the same thing (: lol

  • Jaron says:

    Xenia may grow fat but it is also a nutrient sponge that is in many people’s sumps to remove waste. It is much better looking than macro algae in my opinion.

  • Robb says:

    Anthelia and Kenya tree should be added to this list as well.

  • Gary says:

    Mark, I would also love to see/read about different types of coral you would recommend to people moving from the tank dabbler world to the reef enthusiast world. There is a lot of information out there, a lot of which contradicts with it’s self. I’m one of those people who like to know everything they possibly can before changing something in my tank.
    Love your show and website.

  • Casey says:

    Old thread, I know. Had to chirp up though…just about EVERY “eww-ick-ey” mention here is in my tank. Why? I like em’. I do find the “spread like wild-fire” stuff kinda’ humorous though. I keep tarantulas and thus I have perfected the art of “patience”…and so “wildfire” just doesn’t have the same ‘zing’. heh. I’ve got a wall hammer on one side…a kenyan tree front and center, three mushrooms 1. green 1 red and 1 blue….a beautiful p. xenia which is doing splendidly…a teal paly frag AND a green paly…. oh and a healthy green star colony.

    I think more than “don’t have em”, it oughta’ be: “pay attention to placement, needs, and growth rates”. Everything on the bad lists here…are beautiful and if managed properly can turn a reef tank into an eye poppingly beautiful display.

    Then again, I keep 15 tarantulas, so hey. 😀

    p.s I also keep Dragon’s Breath in the DT. nyah! 😀

  • Miles says:

    You forgot blue Ridge.! Will overgrown everything!!!

  • Tony Manias says:

    Great article Mark!! Thanks

  • Jake says:

    I added one green mushroom to my tank 3 years ago.

    Now I have over 100 taking all the realestate, and block the holes in the rock where my blenny likes to sleep.

    What a PITA. There is no way I can epoxy over them either, it would take several tubes of epoxy and leave my tank looking like I had a bad shaving experience

  • Scott says:

    I have just bought an established 75 gal reef tank with several colonies of PomPom Xenia. I’d like to thin the herd, how do you go about it? I have several frags on smaller rocks that I might take to the pet store but others are covering the tops of several larger rocks.

  • Scott..Xenia is near impossible to eradicate. Best bet is to completely remove the rock that it is on.

  • Felicia says:

    I have more Xenia than one enthusiast could ever need! I’m giving it away to anyone who will pay for shipping;-)

    My email is if you want pics or vids just let me know! Happy New Year!?

  • Kris says:

    Blue cloves are the ultimate pest! They choke out corals, zoa, SPS etc….

    Never add them! They spread like wildfire.

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