How long can parasites "hide" on a fish?

[MCCOOL]

Hello,

I recently acquired a geometric Pygmy hawk (Plectranthias inermis) from a friend who has had it for at least 6 months. It is currently in my QT being treated with cupramine to keep my tank ich free.

*Should I go ahead and treat it with PrazioPro, or is it unnecessary? Would internal parasites have already shown up if the fish was infected?

Thanks for any help