>>> are they true sharks
If by "true" sharks you mean in the same family as things like the Great White, Hammerheads, Reef Sharks - that kind of thing, no, most definitely not. The true sharks and rays do not have "bones". Their skeleton is made of cartilage, (the flexible stuff your nose is made of for example). The sharks and rays belong to a different Class of fish called Chondrichthyes.
The vast majority of the rest of the worlds fish belong to the Class Actinopterygii, which in addition to having real bones, have rays in their fins, this would include the Cyprinids you speak of.
There are 3 other Classes of fish, but these Classes together hold only a few Orders, Families, Genera and Species. The only thing your remotely likely to see from these Classes is the occasional Lung Fish.
The Rainbow and Bala sharks are both members of the Family Cyprinidae, but belong to different Genera. They are related at the Family level.
The science of "naming" is called Taxonomy - it has a very rigid structure, but can be mightily confusing because the very precise meaning of a word in taxonomy may not be reflected in the day to day use of the same word!
?)
