HELP I have sea spiders!

Jared Cooper

New member
I looked at my SPS tonight and one coral is covered with tiny sea spiders. They are maybe a 1/2 of a cm. What do I do???? From a flashlight they look brown. This really sucks.
I had a plague of sea spiders eating a Goniopora from the bottom up. I looked online and couldn't find any info as to what to do. I ended up using the Goniopora as bait and very few days I would pull the Goniopora from the tank, place in in a black plastic box of tank water, and search out every one of the little blood suckers under with the aid of desk lamp and tweezers. It was too slow to smash them, so I would just pick them up and wipe them off my tweezers onto the newspaper I had spread across my desk. Then I would dump the box fuul of water in the toilet and put the Goniopora back in the tank. A black background & bright light will help you to see the little s****.

The only info I found mentioned that larval sea spiders may live as parasites inside the tissues of coral, so yours may have come in on one of your corals.
They are too small for my camera but I KNOW they are sea spiders, there is no question about it. They match pics in my Fossea's vol 3 book.
Thanks for the advice. Dr. Ron said the same thing. Looks like I am screwed. I'll pluck as many as I can tonight. If this gets really bad I am done with SPS.

What kind of LPS are they after?

I wouldn't give up, really, I know it looks bad but I only picked them off my Goniopora 3 times before the plague ended. I thought it was hopeless at first cause a lot of the sea spiders I found had big egg sacks, but now everything is cool and the tissue on the coral has grown back.

Now I just have to worry about feeding this coral now. :rolleyes:

I would trade you your sea spider plague for my Caulaerpa racemosa plague any day!!;)
There's nothing that eats them? What about soaking the corals in an iodine solution such as Tech-D? It won't hurt the corals, but I'm wondering if it will tox out the spiders.

I don't know a thing about this...just wondering out loud.

~ Sherri
I am glad to hear that your tank is doing OK from the spider damage. They are actually on my SPS, specifically my Acropora Humilis.
I was wondering the same thing. As far as dipping the corals, I don't think the spiders live on the SPS cause I only see them at night, specifically after midnight, on the corals. I think they hide in the LR. Also my SPS have encrusted onto my very large pieces of live rock so it would be hard to take them out. Dr. ROn said that he did not know for sure of any predators and that basically I am screwed. I am gonna send him some some of the sea spiders.

If this gets real bad I am gonna get ride of everything, my fish, rose anemones, and corals in my 120 and dedicate it to a Heteractis magnifica and a few clowns.
Ugh! What a terrible thing to battle. I certainly hope the spider infestation doesn't cause you to sell everything (but if it does, may I buy your rose anemones?). Surely you wouldn't want to give up your anemones even if the spiders damage your corals, right? I hope you're speaking in a moment of frustration and it never comes to that point. I don't believe in luck, so I'll say a prayer for the demise of the sea spiders. :D

~ Sherri
I'd get ride of everything to make room for the ritteri. I am sure the spiders won't touch the anemones. I am mostly speaking out of frustration but I am serious about it if the spiders eat my corals and I can't get rid of them. I've always wanted a tank dedicated to a ritteri with a few clowns. That way I get feed it a ton and get it to grow to a huge size and enjoy it in all its glory:D OK I'll stop, I am getting a little poetic.
An old post but helpful info .

I found 6 of them on an acro that had acro eating flatworms . I found them during a tropic marin pro coral cure dip .It killed them .


i had sea spiders, my LFS suggested a six-line wrasse. he loved them and stayed bloated till they were gone. they seemed to make him mean to other fish that got near his snack. (red goniopora)