Sea cucumber hitchhiker

[Hross]

Sorry if y’all don’t consider this true emergency but: Bought a pulsing Xenia today at the LFS that looked as if it was on a pretty dark purple rock. Nope, when home found it was a big fat sea cucumber. My tank is 125 gallon and 2 weeks old. I do not want this thing that will likely die in my new tank and kill everyone in it. I have it in an acclimation box until I can bring it back on Monday. How can I take care of this thing so it doesn’t die before then? I put an algae wafer in the box. Rubber band so it doesn’t get out (I don’t want it to go hiding in my tank). It’s been in the same position for a long time, that normal? Help me be a good host for the weekend until I can bring him back!

 

[ISpeakForTheSeas]

Any chance you could get some clear, close-up pics of the cucumber under white light?

I ask because there are basically two types of sea cucumbers: filter feeders and sand-sifters. The filter feeders need fed things like Isochrysis galbana (T-Iso), Tetraselmis sp., Thalassiosira sp., and Chaetoceros sp., while the sand-sifters should do find on pretty much any tiny/ground up food (pellets, frozen, etc.) with plenty of greens (phytoplankton/microalgae and/or macroalgae) added in - you just want to make sure the mix reaches the sand so that they could sift the sand to get the food; you could do this by using sinking feeds, or by mixing the feed in with some sand in a dish that you take out and put in to the tank at feeding time for the cuke:

With regards to the sediment feeding cucumbers, as mentioned, you can ghost feed the tank and they'll do just fine on that. For example, the Chocolate Chip Sea Cucumber (Isostichopus badionotus) has been bred in captivity on the following diets*:
"Two feeding protocols were tested: In the first year, the broodstock were fed with commercial tilapia and rabbit feed which was ground, supplemented with Spirulina powder, and blended with disinfected beach sand (30g food/kg sand). In the second year, the food was changed to a mixture of ground Ulva sp., Sargassum sp., and Macrocystis sp. meals (Baja Kelp, Ensenanada, B.C., Mexico) blended with disinfected beach sand (30g algae mixture/kg sand). The food was changed every third day to prevent fungus formation."

I don't remember the other species I've looked at at the moment, but, generally speaking, sand sifting sea cucumbers are not picky about what they eat (though the food likely needs to be relatively decently sized so as to fit in with the sediment they're sifting - for example, the food they fed to the juvenile sea cucumbers when they reached 3 cm in the study above was sieved 55 at microns). Some easy foods you could offer that should work even for smaller cucumber species would be things like TDO Chromaboost Type A and Spirulina powder like used in the study I referenced.

If you do want to keep sea cucumbers, make sure you're tank is prepared for them (i.e. make sure the mechanical parts of the tank won't kill the sea cucumber), and make sure you know about the risks of keeping them (which are mostly to any fish in the system with them).

That said, from what I've seen with other people's tanks, I'd agree that Brittle/Serpent stars, sand sifting sea cucumbers, and some urchins are probably the easiest echinoderms to care for (possibly in that order) - starfish (with the noteworthy exception of Aquilonastra spp. stars, commonly erroneously called Asterina stars in the hobby) and crinoids are basically considered impossible at this point (though a number of coldwater starfish species have been aquacultured successfully, so if you want a coldwater tank, you do have a few good options there for starfish). If you really want a true starfish in a tropical tank, you can add some Aquilonastra stars (though they are often considered pests due to their typically quick reproduction rates, and some people believe they eat corals - specifically zoanthid corals), or you can try a sand sifting starfish (I don't recommend it, but if you want to try it I do have some feeding suggestions that may or may not help with long term success - no one has gotten back to me yet on if it has helped their stars or not, so I don't know for certain).

*The study:

https://onlinelibrary.wiley.com/doi/epdf/10.1111/jwas.12061

Edit: It sounds like a fun project to me - good luck, and welcome to Reef2Reef!

 

[Hross]

The little darling made it and is at the LFS awaiting his new home . I kept him in a bucket with water changes and an algae wafer.