crabs?

[Fishmommy]

Is there a downside to keeping crabs in a reef tank? I read somewhere that they are essential to a clean tank, but have also read about aggressiveness problems. What is the verdict?

 

[tatuaje08]

Generally, the smaller red leg and blue leg hermits are ok. A lot of the different crabs could go either way. You just have to keep your eye out.

 

[rssjsb]

With the possible exception of porcelain crabs and other filter-feeders, any crab has the potential to cause problems in your tank. Hermits will kill and eat snails. Sally lightfoots and arrow crabs get ornery as they get older and can kill fish. Emerald crabs can also be a problem.

The fact is that most crabs are opportunistic - if they're hungry and have a chance for a quick meal, they'll take it. To avoid this problem, a lot of people run their systems crab-free. So I wouldn't say they are essential to a clean tank.