What is wrong with my betta?

by Chris Devers
Question by Phoenix: What is wrong with my betta?
I have had a male red veiltail betta since mid May this year, so not very long. After the first two weeks, I noticed that his tail was becoming shorter and shorter. I cleaned 50% of the water of his 3 litre (0.8 gallon) "tank" (unfiltered, unheated), which I know is not a real tank, it's not big enough. It is the Marina Betta Kit. I listened to the pet store people who told me that bettas liked living in smaller cups, but

depression and anxiety scale