What were its tankmates?
Man that sucks, sorry to hear that
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I don't know if you should put him down or not ,i have a 1 eyed congicus I got him that way,he is very very stubborn when it comes to eating but other then that he has been fine
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Yeah def the knife. Maybe do a little more research before buying.
I had a ghost knife a loong time ago eat a fish eye but it was casue it was a smaller fish and i have been keeping fish for years..