This is a separate tank for sea apples, to keep them safe and others - safe from them



Refugium type of the tank, to keep biodiversity high.

Tank setup:
10g tank, BB, LR rubble was siliconed to the back wall by Marine Goop (not a good idea, kills LR and not a good hold as time passes) - tank was started as sun coral babies grow out tank.
Side sump on the left, small AquaFuge-like HOB acrylic refugium, filled by Seachem Matrix biomedia and LR rubble, contains also heater, return pump, micron sock and carbon.
Red Sea Nano Skimmer, looks like HOB power filter - on the right.
Additional pump - under sea apple, slightly aside - to create flow, that brushes sea apple's tentacles sideway.
27W daylight CFL from hardware store, could be any other light.

Problems:
Aiptasia, bristleworms. Berghia nuibranchs and their babies didn't survive there.

Frequent feeding for sea apples (two of them, small is >2", when closed, large - 6"+. Have them for almost an year).


Variety of food, both phyto- and zooplankton, mostly dried, and live super small rotifers.

Other inhabitants hitchhiked on pieces of LR:
red mushrooms, yellow polyps, Kenya tree (problem when it stars to drop branches), gsp, macroalgae.

Add your sea apple tanks

great idea. Nice looking apples

So neat, I wish I could do this. Cucumbers are cute I'm only planning on adding a yellow to mine. The aren't deadly if they don't make it. I have a large droll-colored burrowing one in my tank now too, but I doubt it's a planktonic feeder.

Filter feeding sea cucumbers look similar, here is pink-green cucumber, either Pentacta anceps or Colochirus crassus (sp?):


I have seen in LFS the pink-green cucumbers of two kinds: fine brighter colored (as mine on the photo above) and large crude paler ones. Still don't know, who of them is who.

Your yellow will be Colochirus robustus, as I understand.
I also tried to find it, but bought by mistake a large golden sand-sifting cucumber: when contracted and on the top of the tank, it looks very similar.


Here is difference in tentacles of the filter feeding and sand-sifting cucumbers:

wow beautiful. how long have you had them.

1 yr sea apples (still have them now) and 4-5 months - pink-green filter feeding cucumber (lost in the tank crash 2 yrs ago).

Sea apples have noticeable difference: they close, when somebody walks near the tank, pink-green - not, and big apple is fist sized, while pink-green was thumb sized, more worries to be able supply enough food for maintaining such big mass. Remember, that all they eat - a very small particles. Fish of this size would eat a tablespoon of food.

BTW, on the web were posted at least two cases of sea apple's disease (1, 2).
None of this for pinkgreen one, but if you serpent stars start losing their arms - cucumber will follow next day, remove them in time in hospital tank with frequently changed water and carbon. Echinoderms alone, without nudibranches or LR (last may carry toxins inside). If this matters, both pink and yellow cukes were not toxic, when died, all corals in the same hospital tank survived. Echinoderms just more sensitive.

Update: tank was overrun by aiprasia, that was out of reach - behind and under the rock, massive frequent treatments and decaying aiptasia sea apple doesn't like and closed for a week. Moved them in the temporary clean tank, 5g, together with skimmer and sump with biomedia. Will add rock as soon as it will become freed from aiptasia. Big cuke opened next day, small is near it - in the middle of the tank:


I already tried berghia nudibranchs, they didn't survive.

have you tried peppermint shrimp, i hear they are great for aiptasia and theyre fairly cheap, not sure if they would bother the sea apples but since you moved them to a different tank this doesn't matter
BTW sweet setup

I'd love to do a tank for some,saw them when I was snorkeling and they are the coolest invert I've seen so far.

I think sea apples look awesome! always been afraid of the whole "if they die in your tank, your tank dies" kind of thing though.