Sea Cucumber - be warned!

I alluded to this in responding to @Fence13 post on his coral issue so thought I would elaborate on our tank issue.

It started with getting a large sea cucumber from a friend who was shutting their tank down several months ago. They had the animal for several years and, I have to admit, it was a cool critter so we took it without doing any real research. We liked it so much we added another small one when we ordered a CuC shortly thereafter (again, no research). I had heard they had some toxicity but having never heard of one causing real issues and a system with 400 gallons of water, wasn't overly concerned. Boy was I wrong.

Came home from church Sunday and noticed the tank was slightly cloudy - thinking the ATO might have kicked in a bit more kalk than usual (but water wasn't too cloudy so wasn't overly concerned about a kalk overdose) I walked over to the tank to see most fish were dead or struggling mightily. Needless to say, we panicked wondering what the heck was going on. Wracking my brain to figure out what could possibly have happened - no kalk overdose, all parameters tested fine. Called a friend who suggested it might be a bacterial bloom - presumably from overdosing vinegar but all dosing container levels were normal so it didn't seem like the doser freaked out and OD'd alk or vinegar etc. No kids in the house to have dumped something in it. We are very careful about no cleaners/chemicals near the tanks so could not figure it out. That was the worst part, just not knowing what had decimated our fish.

Then the skimmer pump quit working. At first, I thought "great, when it rains it pours" then I pulled the pump out and took it apart for a vinegar bath and noticed a lot of tough, rubbery tissue all caught up in the impeller and was perplexed...until Deanna said "didn't we have a cucumber?" and then it clicked....(see pic below of remains)

I did 115 gallons of water changes and added 5 lbs of carbon to the sump but was too late for most fish although corals and anemones (we have several BTA's and a ritteri) seemed only minimally affected. In fact, the clowns seemed completely un-phased making me wonder if they have immunity similar to with an anemone. At any rate, only our pair of clowns and mandarin survived.

We lost:
- 11" male Naso tang (RIP lips)
- 7" PBT
- 6 lyretail anthias
- 3 Bangaii cardinals
- matted file fish
- 4" purple tang
- lubocks fairy wrasse
- "red" fairy wrasse
- black cap basslet
- royal gramma
- black assessor
- chalk basslet
- splendid dottyback

Needless to say, a very costly lesson. Be sure to research any animals you add to your tank and be sure you are prepared to assume the potential risks. If the other cuke turns up you will see a "free to good home" post on this site 5 within minutes.

 

We dont know as we rarely see either of them.

 

Great question and one I can't answer other than the fact they have no bones so must be able to flatten out very thin to get in the overflow.