Fluval FX6 High Performance External Canister FilterExternal filters are an excellent option for medium sized aquariums and upwards. Their large size and power means they are the most suitable option for larger aquariums, or those that are heavily stocked or house messy fish which produce a lot of waste. Excellent for aquariums housing large and or big groups of cichlids, carnivorous fish species, oddballs, stingrays etc. They are also a great option for those who wish to invest a bit more in a