Could i possibly add 6 cardinal tetras to my tank?

yes you could add them anyway. but taking the fry out would be good. they would most likely eat the fry, thinking they were worms. tetras will become a big shoal. they like to how do i explain get lots of different types of tetras and make a big shoal. you could get 3-5 cardinals and they'll go with the neons which are eating the fry too i bet.