A 75 gallon tank is suitable for housing a large number of cichlids, however the exact number depends on the size and species of fish. For example, smaller or less aggressive species such as angelfish can be housed in larger numbers than more active varieties like jack dempsey's or firemouths. In general, it is recommended to keep no more than 15-20 adult cichlids in a 75 gallon aquarium. If you plan to add juvenile fish later, it is best to reduce this amount even further. Additionally, make sure your filter system has sufficient capacity for the increased bioload that comes with stocking so many fish.