fresh water tank already been astablished eons ago

Lupin

I will have to add that tiger barbs will nip when kept in lesser than 6. The smaller the space, the bigger chances they'll nip.
They need to be kept in 8 or more in a large tank as tehy established hierarchy among themselves.

Another advice: Don't believe in anything the lfs say. Do the research yourself or ask for experiences. It's never too bad to ask others of their experiences.