It was all going well untill I woke up today morning, one of my goldfish had red spots over the fins and gills, another one had a little red spot on the fin. I thought it could be ammonia poisoning (but I had changed the water just two days back) and changed 50% of the water and added 5ml of rid all general aid. I was researching about it and found it might be helpful to feed fish with live food. I took two red ants( who were already dead and floating in a bucket) washed them with fresh water and fed one to each. They chewed it for some time, than spit it, than again chewed it and finished it. After an hour or so one of my goldfish was lying at the bottom with mouth open and rarely breathing. I instantly added salt and 15ml rid all general aid to the tank. It was rarely moving fins, after half an hour, it died. The other goldfish (that had just one red spot) is still swimming actively. Did this happen because I fed ant to the fish? I feel so guilty for killing my goldfish and don't know what to do. My tank is 120 litres and had 2 goldfish in it (now just one). Please let me know what could be the reason?