are they standard or glass bloodfins? the glass ones have less red in the fins and seem to be the one sold most commonly now. i would get at least 6 of them, they like company and will color up better in a group. going to replace my rummy nose and cardinals with them as they die off in my large planted tank, they are much more active and i love the flash of silver and red.
you got glass bloodfins, the fins will never get as red as the standard bloodfin. i you want more red, i would go out and get the regular silver ones. they will do fine with the ones you already have, i mix green fire bloodfins (slight green tingeon body, and white tips on the red fins) with my regular bloodfins and they are ok.