I have a one year old sting ray who has recently been acting weird. He's been doing great until about 2 weeks ago. He is a smooth river back sting ray. We do 50% water changes at least once a week, if not twice. We have two C5-30 filters running on his tank and he has no tank mates. We noticed he had a death look to him, eyes were black and he was swimming in very odd circles in the tank, not like himself. We did some emergency water changes and he made it through that. about two days after that he stopped eating and hasn't been eating since. Now he has started swimming erratically around the tank, bumping in the sides of the tank and the top lid. Water parameters are good, but not sure why he isn't eating and swimming so erratically. I did notice this morning his poop was green, almost looked like sea weed. Thanks for any help.