Only time will tell now that you have it.Give the big guy a day or so to settle in and then do a good water change and hopefully the eye will clear up soonafter.In the mean time see if you can find out from the previous owner how long the eye has been in that condition.
on his other eye the ball part is good its just little on the outer looks cloudy
im not sure how long i think a week or 2 when i was orignally gonna buy it he was fine but i texted him a week later he said the wolf fish attacked his eye or bichir i dont know whichone
hopefully i can cure him
ill take him to my eye doctor maybe he can remove it LOL