I have a 10 gallon tank for 1 telescope butterfly. I knoww its a small tank for my goldfish but I keep track of the quality of the water by testing now and then + 50-70% water changes every 3 days and have a 150gph filter running. She's still fairly small but yes I do plan on upgrading her home. But my question was if goldfish depression exists? She's sleeping most of the time( no she doesn't sleep/stay at bottom of the tank) she's just floating about by herself. She only gets active when I feed her.. I wonder if she's lonely? If goldfish depression does exist tho I'd have to get a bigger tank sooner so I can buy another goldfish as her buddy.. Im just worried haha but seriously she's just sleeping way too much for a goldfish.. Even with the lights on? Is that normal ? Lol