The crayfish need an “internal or external canister filter” in their fish tanks to provide the prime environment for growth (Pierce n.d.). A canister filter continuously cleans the water within the tank to maintain the ecosystem for the crayfish. An internal canister filter hangs inside on the glass tank, while an external canister filter hangs outside on the glass tank. These canister filters are the best option for a fish tank because, without them “20-30% of the water” in the fish tank would have to be “changed daily to get rid of debris, feces, and uneaten food” (FishGuy, 2012). With these filters present, the caretaker does not have to change the tank water every day, but it would be in his/her best interest to change the water at least
