It is often thought that cichlids are poor community fishes. In fact, with few exceptions most cichlids can do well in a community tank set up. The trick is to choose cichlids that will thrive in the size tank chosen to house the community. Cichlids, range in size from about 1 inch to over 3 feet long. Even the biggest cichlids can be housed in a community tank if the aquarium is large enough to accommodate them at their largest size.
Piranhas are probably the most difficult fishes to set up in a community tank.
However, once the habits and ecology of these fishes are understood it should be simple enough to set up a community tank with piranhas. This tank could be planted with a specimen of Amazon swordplant, a number of pygmy chain swordplants, several corkscrew val plants and other background and foreground plants. African root wood pieces would make decorations and add to the available hiding places and provide potential spawning sites for the small cichlids. Expect the cichlids to reproduce and thereby increase the tank population. Use several pounds Texas holey rock and pieces of African root wood to provide plenty of hiding places for female and juvenile fishes.