Good Compatability
An aquarium can only be a success if everything inside of it gets along. Not all fish are compatable with eachother. Aggressive carnivores, such Oscar Cichlids should never be put with small fish, such as Neon Tetras or Rosy Red Minnows. Only semi-aggressive fish are the only type of fish that can be kept with cichlids, as cichlids are the most aggressive aquarium fish. Non-aggressive fish, like Guppies and Mollies, can be kept with most semi-aggressive.