Appear to be tetra's of type I am not sure of.
Can say that so long as fishes are not being nipped, that twice weekly water changes for a few weeks should heal tattered fins without the need for any further treatment.
If fin nipping is occuring and you have the room,then adding a few more to the three you have may spread the nipping around.
Schooling specie's often nip at each other while establishing pecking order and the more fish in the school,,the less likely that one or two can be singled out.
Can't stress the water changes enough to help re=generate new growth on fin's and prevent secondary infection's from setting in.