Do you have an API fw
master test kit? If you dont, you should invest in one as soon as possible. Until you are able to monitor your water parameters for ammonia, nitrite, & nitrate, you should do 50% water changes daily with temperature matched, conditioned water. He is suffering from toxic water conditions in too small of a tank & his eyes are being burned. Fancies need atleast 20gallons for the first fish, 10gal for each fish after. Healthy water should be enough to clear his eyes if they are not infected.