The biOrb bubble tube guard is a clear cap which sits over the top of the bubble tube to prevent objects and fish from getting into the bubble tube. Holes in the cap allow bubbles to come out.
It is very rare that a fish would go into the bubble tube, however some fish like to try and squeeze themselves into the most unlikely places. Just in case one of your fish enjoys this behaviour we have the bubble tube guard. The guard will also prevent bottom feeding fish such as catfish from getting into the tube, however, we do not recommend keeping these types of fish as the ceramic media in the biOrb does not provide a suitable substrate for them.