Sorry to hear about your prized betta, I remember seeing your post on him just a few weeks ago...=\
Right now the only fish I own that would probably actually -really- bother me if it died is my Dwarf Puffer, who despite his size has the personality of some of my co-workers. Next down the chain are my kuhli loaches, though I rarely see them anymore. One of which committed "suicide" several months back, when he overgrew a tag hole, or air vent although I can't imagine why you'd place an air vent at the base of a fake ornament..(hiding spot) ...and decapitated himself trying to get out. Perhaps its easy to understand why my tank is completely natural now, other than mechanical necessities. heh