Betta Fish: Thanks to this subreddit; I decided to give Milaneso his own 10 gallon tank. Now everyone is much happier.

It was a night and day change in the behavior of the Betta and the shoaling fish. Now Milaneso stopped glass surfing; his cloudy eyes are gone; and the rasboras and tetras shoal together; with much less aggression between them. Now it is finally relaxing and enjoyable to watch the tanks. Thanks everyone!