Mar 3, 2009

Pom Pom Crabs - Perfect Nano Crabs

Since Nano aquariums have become popular, hobbyists are always looking for tiny, peaceful animals to live in them. I think crustaceans make excellent Nano tank inhabitants because they produce less waste than fish and need less room.

One deserving Nano crustacean is too often overlooked because it is cryptic and nocturnal - the pom pom crab, Lybia tesselata. See one of my pom pom crabs pictured below.

pom pom crab

Probably the most fascinating aspect of these crabs is their symbiotic relationship with tiny anemones of the genus Triactis or Bunodeopsis. The crab holds the anemones (which contain stinging nematocysts) in each claw and uses them for defense. These crabs literally pack a powerful punch. I once saw one of my gobies try to evict my pom pom crab from its hole in the rock when the crab "punched" the goby in the face with its anemone. There was no permanent harm, but I'm sure the goby will think twice before trying that again. Pom pom crabs also use their anemones' sticky tentacles to help them "mop up" food. This feeds the crab, and in turn, feeds the anemones. The crabs mostly eat meaty foods and are considered aquarium scavengers. They should be target fed in the aquarium.

Pom pom crabs are naturally nocturnal and very cryptic. When housed in a large or medium sized aquarium, they will rarely be seen. The best time to view them is at night, with the lunar lights on. The crabs are very hardy and can be housed in a small aquarium with no problem. However, the anemones can not tolerate unstable water parameters and often die shortly after being added to an aquarium. Nano aquariums are known for having unstable salinity and water parameters. This is why it is best to add your pom pom crab only to a well established, stable Nano aquarium. An auto top off system can help with this.

pom pom crab with eggs

If your pom pom crab loses one of its anemones, it can split the other in half and make two anemones. If your pom pom crab loses both anemones, it will still survive, but may start chopping up and carrying around your Zoanthus or coral polyps. If you have more than one pom pom crab, these social creatures will actually share anemones. If a crab loses both anemones, its generous "friends" may cut one of theirs to give.

Some people consider these crabs not to be reef safe because of the stinging power of its anemones. I believe that since the anemones are so tiny, they pose no threat whatsoever to healthy corals or fish. I even keep mine with seahorses and tiny gobies.


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