By Bob Goemans
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Bob Goemans corresponds with Jerome A. Fried

Jerome A. Fried writes...

Hi Bob,

First, let me say that your articles are comprehensive and informative, and the best I have found on the Internet to date!

That being said, I recently added a pink spiny sea cucumber to my 28 gallon NanoCube tank. Since then, some of it's coloration has faded, and it looks like it is constantly convulsing - bulging out in some parts of the body and getting very constricted in others. It moves, but not much, and seems to be constantly in the 'threatened' posture - all tentacles extended all the time. It shares the tank with four small damselfish and several snails, and four porcelain crabs. Is this the type of cucumber that has a greater chance of poisoning the tank and is there any way to tell if the cucumber is dying, or whether it is healthy, happy, or otherwise? Do you have any tips for its care?

Jerome A. Fried

San Francisco, CA

Bob replies...

Hi Jerome Fried,

Go to my website and open the Animal Library, then to Sea Cucumbers. Then open 'Filter-Feeding Sea Cucumbers and find the species Pentacta anceps. If this is what you have, it's a suspension feeder, in other words it filters the water for nutritional matter, much like Sea Apples and as described there for these type animals one must add various plankton-like additives to maintain their health. Keep in mind this creature does not sift sand for organic matter, therefore, you must care for this type creature as mentioned above. But if you do add additional foods to the bulk water, then it's a must you monitor water chemistry, because in a small aquarium, it can go downhill quite quickly if not careful.

Furthermore, shrinkage, color fading, and/or undergoing odd form changes are a sign of poor health, probably due to insufficient nourishment. And yes, I would not risk it dying in a small aquarium!

Hope this helps,



Sea Cucumbers

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