The disclosed embodiments include an aquarium having a non-disruptive filtration system. In one aspect, an apparatus includes a tank having a closed end and an open end, a lid removably positioned over the open end, and filter housing including a sidewall that, when fixedly position within the tank, encloses a first portion of the tank. Inlets in the sidewall maintain fluid communication between the first portion of the tank and a second portion of the tank. The filter housing includes a filter cartridge partitioning the enclosed first portion into a first chamber from a second chamber, a pump disposed within the second chamber, and a reservoir disposed within the second chamber at a distal end of the filter housing. The reservoir is connected to the pump across an elongated tube, and includes discharge lip across which pumped water discharges into the tank.