There is the Betta smaragdina or Peaceful Betta, who do not attack each other unless competing for the attention of a female. They are being more commonly sold now and some of the books are beginning to say that they may someday replace the Betta splendens as the most commonly sold Betta.
The Betta splendens is the Betta that I am sure most of us have here and is divided into the various fin types of: Veiltail, Halfmoon, Crowntail, Delta, Superdelta, Doubletail, Combtail, and other fin types. There are many more species of betta that you will never see for sale or in any fish exhibit simply because they are rare or exist only in the wild. There are others that do not lend themselves to aquarium life and are not attractive so would not be commonly desirable. There are others that are bred especially for fighting which is why the Betta began to be kept by humans after all.
I hope this information is helpful.
Rose
