When to start metro and worming on 6week old fry?

[bornlooser]

Hi
I have batch of around 50 Red Melon fry that are 6 weeks old (1st batch)..like to know when i can safely start preventive meds for internal and external parasites.
thanks

[Chicago Discus]

If the Parents are clean there is no need to medicate them wait until you see a problem.....Josie