Don't think this is an emergency but My oscar is showing signs of sickness. I don't have a lot of experience so I need help with what to do. He keeps running away to the end of the tank and sitting there everytime I come in the room. Also he sometimes will be almost straight down with his tail almost straight up and then he will idle normally. He no longer comes out and "wags" when I come in the room. I'm pretty stressed tbh. He also will swim back and forth to each end of the tank. I just changed the water today and tested the water. No signs of any water problems.