Hi, I had 2 goldfish that I got 2 weeks ago. One died 4 days ago. He did not look sick but it was not eating well for a couple of days. I found him at the bottom of the filter. Immediately I changed all the water from the tank and I added antifungal medication to the water. I placed the other fish, who was fine up to that point. Right after I placed him in the water, he started acting funny. He would stay at the bottom, but it can be stimulated by tapping at the glass and it would act "almost normally" but then it would go back to the bottom or just be not as active. It has not been eating as much as before, and now it's hiding behind the vertical filter and barely moving. It can still be stimulated and it would act normally for a while but then it goes back to hiding.
WHAT"S GOING ON WITH MY GOLDFISH???? HELP PLEASE!!!