Just noticed that one eye on my green wolf eel is cloudy. It almost looks like it has a opaque covering. the other eye is fine. She is also hiding more than usual. Checked nitrates they are 20ppm(fish only setup) and PH is ~8.3. Doing water change today(do weekly 20-25 %). She shares tank with a lionfish and he seems to be doing great. Do I wait a while or treat and with what.