They must be spot-fed often if not daily (unskimmed tanks worked best for me). I've kept some for several years before having to give them away (unrelated to their health or system health). Not to say that 3-5yrs is a long time, but I don't see why you couldn't be successful if you take the time every day. These particular cucumbers and other reasonably small species, under 3", usually will not cause much harm, even if they perish; however, larger cucumbers (perhaps excluding detrivores) and especially the infamous Sea Apple I would be wary of. It usually takes quite a bit of roughing up for a cucumber to defensively combust. You obviously wouldn't want to keep it with any predatorial fish (triggers, puffers, etc)...just my experience with them.