Sounds like popeye. It starts out as a cloudy eye and can lead to 2 cloudy eyes. This is not good. The fish cannot see through the infection. It is a bacterial infection, mostly treated with antibiotics. If you dont know whats cause the infection. Usually doin partial water changes, treatment with antibiotics, can help. Personally when my niger got it i used a quarantine tank and highly recommend it. That way u can treat the fish and get it healthy while finding and fixing the cause in the home tank. Ive seen some articles where people have treated with epsom salt. But personally i wouldnt. Id go to ur lfs
and get antibiotics and go that route and start treatment and quaratine b4 it gets to bad and possibly lose a beautiful fish.