never do water changes and change filter media at the same time.. you may get an ammonia spike..
that is really a white eye... similar looking diseases are caused from high nitrates... you need to do a large water change.. like 50-60 percent and then everyday do a smaller 15 percent water change each day until your water parameters are back in check... i don't recommend any chemicals but someone else my say melafix .. if you do use it then i recommend half the dosage. also make sure he eats well but i don't know if you can save that eye.
that is really a white eye... similar looking diseases are caused from high nitrates... you need to do a large water change.. like 50-60 percent and then everyday do a smaller 15 percent water change each day until your water parameters are back in check... i don't recommend any chemicals but someone else my say melafix .. if you do use it then i recommend half the dosage. also make sure he eats well but i don't know if you can save that eye.
with the above