I had a red eye tetra who would sometimes ditch the other tetras to hang out with my rosy barbs. The rosy barbs pretty much ignored him though, poor guy! He eventually gave up and stayed with the tetras.
When I had an angelfish die, my remaining angelfish was lonely and kept trying to hang out with my pleco. The pleco would be sucking on the glass, staying in one spot, and my angelfish would just hover next to him. Then, once the pleco started sliding across the glass, my angelfish would get all excited and swim alongside him. It was so sad! Once I got another angelfish though, all was well again.
