Dwarf fish for example Guppies and Danios, Corydora catfish, pigmy suckermouths, groups of barbs or tetras Most Central and South American cichlids is often retained with a variety of aquarium plants, but African species are tougher to pair as a consequence of water parameters. It is not extremely hard however! https://pearlaquatics.my/product/api-freshwater-master-test-kit/