Sea urchin eating my fish


New member
So, I looked in my tank today and realized my sea urchin is eating a fish! I am sure this is not the only one since fish have been disappearing. Attached a pic. Is this normal? The thing is massive and I am thinking about getting rid of him.


  • urchin eating fish.jpg
    urchin eating fish.jpg
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Grizzled & Cynical
Sea Urchins are a big pain, and I don't keep them in my tank, but hard to see how one could actually catch a fish. Seems more likely the fish died and the urchin is doing its job as part of the CUC.


New member
It is crazy because I've had this urchin for a long time (almost 2 yrs) and never had any issues with it. I've always had fish "disappear" but never seen him actually eat one. On top of that, how did the fish even get underneath him? There is so much turbulence in the water. Either way I think it's time for him to go.... here's a vid of it:


biggliest cofveve champ
i cannot imagine any urchin being fast enough to catch a live fish. if your fish are "disappearing", it's likely they are dead from some other cause by the time the urchin gets to them.

i have a tuxedo in my 29g and a pincushion in my 14g. neither has ever bothered a fish.


New member
I agree with what everyone else is saying, there is no way your urchin killed that fish.

It's actually doing what it's designed to do...clean up.


Saltwater Addict
Your fish died from other causes and your urchin is being a opportunistic eater. In the wild fish will hang out close to their spikes for protection. Urchins have one eye and move far too slow to catch and eat any fish period, not to mention they can't "catch" a fish anyway. You need to figure out what is wrong in your tank to be killing the fish that your CUC (urchin) is disposing of. Be thankful for your urchin, without it your ammonia would be off the charts


New member
Actually, I think it IS possible. I have two urchins. One has very small fine (long) white threads that come out between the spikes. I can easily see a fish sleeping and the urchin attaching itself to a fish while staying "planted" to live rock. Fish gets exhausted and stressed then disappears.

Until you posted this thread, I have had fish "vanish". I am talking about 3 inch tang. and a 2 inch clown. The fish were healthy, eating good and good color and "poof" GONE.

Yes, it is possible that I have a Mantis shrimp but I don't think I do as I recently broke down the tank and left the LR out for 24 hours. I think I am going to get rid of my urchins - although they do a great cleaning job.