Are Yellow Cucumbers (Colochirus robustus) good for Reef Aquariums?

Question

Are Yellow Cucumbers (Colochirus robustus) good for Reef Aquariums? Are they harmful to corals or other inverts?

Answer 1

I've never purchased any of these, but I've had some come into my tanks thanks to live rock.

If you're keeping these in a reef aquarium, you only want to house them with fish that won't try to eat them - they're mildly toxic. Other than that (and releasing ammonia into the tank if they die), they don't intentionally harm your other tank organisms. You will need to block any access into filters, overflows, the heater, etc. because these can also damage them and cause them to release their toxin.

They're a filter feeder, so you'll need to keep that in mind when deciding to get these or not. They will remove fine particles from the water (phytoplankton, zooplankton, the pine particles from the "liquid" portion of frozen marine foods), so these will be used as a food source if available. The problem here is one of balance - they must have enough to keep them alive, but if you overfeed, the presence of the fine organic matter will cause poor water quality, and cucumbers don't tolerate poor water quality very well. So if you don't keep up with your water changes, high nitrate levels in the tank may stress or kill them, causing them to release their toxins.

Answer 2

As far as being "good " for reef tanks I would say no because they dont really serve any purpose. But they are very cool and can be kept in reef tanks and dont pose any direct threat to your corals or fish. The problem with them is that they are filter feeders so they do best in established tanks, even then its been my experience that you still have to supplement fairly heavy with a good phytoplankton supplement. The first batch I had did well at first but gradually withered away. The only real danger with them is that if a fish nips them or they get stuck on pump intakes they can release a toxin into the tank, but they are one of the smaller cucumbers so in a large enough tank the dilution may really minimize this harm.