Treat the fish for the Max amount of time the med. bottle says. Just because u cannot see it, doesn't mean its no there.. I have had thousands of Goldfish & all need to be medicated when u first get them..

U need to open the bag for air & allow the bagged fish to sit in the new tank water for about 30 mins to adjust the temp of the bagged water so ur fishy doesn't go into shock & die.

When I buy my feeder goldfish (300-400 at a time) I treat the fish right in their bags for about 30 mins & then set them free. I use LOTS of charcoal in my pond filter that it breaks down the meds. so it cannot harm the turtle.