Red bugs are tiny little crustaceans that are Acropora pests. They usually go unnoticed until their numbers are so high your corals are struggling, and often hitch hike into the aquarium on new coral frags. These pests usually survive any sort of dipping treatment in normal doses. The best method of attack if you find red bugs in your aquarium is a full-tank treatment of Interceptor. This medicine is actually a heartworm medicine for dogs, but does wonders for wiping out red bugs. Unfortunately, other crustaceans will also be killed. These include hermit crabs and shrimp, but other animals are unaffected.