Yes but you have to be aware of how big they get, because when they grow up to adult size they most likely will start to eat smaller fish.
Most livebearers are tropical fish. They can mix easily with most other community type species including Tetras, Danios, Barbs, Anabantids, Corydoras, Dwarf Cichlids etc.
The Zebra Danio is a good small community fish and can live with just about any fish that is not going to eat it. It will go very well with Livebearers, Tetras, other Danios, Anabantids, Rasboras, Dwarf Cichlids, most Botias, all Corydoras etc etc. the list is almost endless.
Guppies are great community fish and can live quite happily with most Tetras, Rasboras, Barbs, Anabantids, Dwarf Cichlids, Danios, Corydoras and many other species provided they don't get too big and eat the guppies.
Betta fish can flourish in a community tank, however because they are at times aggressive fish (males especially) correct pairing is crucial. Bettas usually get along well with neon or cardinal tetras, platies, mollies, guppies. Stay away from tiger barbs and cichlids, they tend to pick on or even kill bettas.
Guppies and Malawi cichlids should generally not be kept together in the same tank. Malawi cichlids are territorial and can be aggressive, which can stress or harm smaller, peaceful fish like guppies. Additionally, the water parameters preferred by each species differ, with cichlids typically requiring harder, more alkaline water. It's best to house these fish in separate tanks that cater to their specific needs.
Fish of the same location or temperaments. In cichlids keeping them grouped by specific locations (i.e. South American cichlids, New American cichlids, Lake Victoria Cichlids, Lake Tanganyika, Lake Malawi, Madagascar, etc.) helps keep deaths down, though it is possible to mix in some circumstances. There are also what is known as community fish. These are your generally more peaceful types such as mollies, guppies, sword tails, tetras, veritas, etc. And remember, just because a type of fish is suppose to act a certain way, does not mean all of them will.
red parrotfish? Well the reef species eats live coral, and the red parrot cichlids eat regular cichlid fish food. You're question is too vague.
African Cichlids are from the Great Rift Lakes of East Africa. Mainly Lake Malawi and Lake Tanganyika.
These fish are laboratory made creatures but they still have some of the instincts of real cichlids from the Amazon.They are egg layers. They do not have live young so they can not get pregnant. My guess is that the larger fish is simply bullying the smaller one.
They may be able to eat them but I very much doubt if they would live on them for long. Jack Dempseys are cichlids and should have a diet to suit including live food such as earth worms.
Most African cichlids are from the Rift Lakes in the Great Rift Valley, and they require very specific water chemistry. Although their water contains some salt (sodium chloride) it also contains other salts of potassium, sodium, calcium and magnesium. Rather than being salt water, it is very hard water. So to answer the question - no, African cichlids can't live in the kind of salt water that is used in marine aquariums. However, most of them (with a few exceptions, such as the hardy kribensis) can't live in true freshwater either. They need water that matches the chemistry of the Rift Lakes, which is unlike any other body of water on Earth.
yes