Our Beta fish loves to play dead. He will float on his side or upsidedown at the top and bottom of the tank. He also likes to hide in trees and under the filter. We constantly have to tap the glass to see if he's alive. He's been like this since we got him. I didn't think much about it until my friend says "Maybe he's just so depressed he wants to die." I never thought fish could be depressed. I looked it up and its a thing! Fish depression is a real thing.