Can I treat my 350 gram shubunkin with my amoxicillin I have on Hand? He had popeye for at least a month. Im doing water changes every third day, using aquarium salt regularly. He's in a tank with his friend. 450 gram goldfish who has no sign of Popeye so it doesn't seem contagious. I'm afraid to use the human Amoxicillin until I know it's safe to do so. I have 500mg capsules on hand.