I have a pond with 2 koI and a pleco. They have all been in the pond for almost a year with no problems. the other day I found the Pleco on the side of the pond with his head halfway out of the water. I put him back in the middle of the pond and he started swimming around like he couldn't see and was bumping into everything and eventually made his way to the top corner with his head halfway out of the water. After a few minutes it seemed like he couldn't keep the suction going and floated over onto his side and stayed like that. I took him out of the pond and put him in a quarantine tank. He can't get his head out of this tank so he just floats around and looks dead. If you touch him he swims around like nothing is wrong but still bumps into all of the walls. He can't seem to stay attatched to anything. He eats fine and I tested the water for absolutely everything and the water is perfect. The water is clear and there is plenty of filtration and there are 2 waterfalls. I thought maybe it was stress but the water is fine, the other fish are healthy. I looked everywhere and can't find any answers. He has been like this for almost 2 days. I have no idea what is wrong with him.