amoxicillin

It is surprisingly frequent the use of antibiotics on DIPs these days. Some users know me as a reefer only, but I am also a doctor. I will not enter the discussion on holobiont and why bacteria are important for the corals… But I would like to create a HUGE ALERT about dipping corals on...

I have a 5 gallon for a single Betta fish. Would the entire Amoxicillin 500mg dosage be too much or should I split the capsule in half ?

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...