"Rams" refers to the common or blue ram which has several varieties but all are the same species, Mikrogeophagus ramirezi. The other "ram" is the Bolivian Ram, M. altispinosus. The former needs warmth, no less than 80F/27C but preferably 28-29C/82-84F. Many other fish will burn out at this warmth permanently, so tankmates are a bit of a challenge. The Bolivian manages at more usual temperatures around 25-26C/75-78F.
Water parameters need to be known. All South American dwarf species are soft and acidic water fish, though a few can do well in moderate hardness and slightly basic pH.
If the 125 liter (33 gallon) tank is 36 inches/90 cm in length, most of the dwarfs will work. However, only one cichlid species per tank, there is not sufficient space here for territories with multiple species.