Spartan: doesn't care as long as he gets his food and the fish/critter doesn't nom on him or bump him. If he weren't older (3 in February) or have that tumor I'd give him some mellow buds. But for now, only snails :) he used to be in with balloon mollies, male and female guppies, leopard danios, apple snail, minnows (temporary thing), regular mollies, and tetras.
Voldemort: he acts tough. He's really a wimp - who can jump high. He'd pick on the little guys (small snails, shrimp) so he'd have to be with equal sized mild mannered fishies and possibly larger snails.
Maine: an escape artist who has to be 100% by himself. No anythings for him!
Sasuke: he's a definite meanie. Anything inanimate gets bullied in his container other than rocks and plants (an accidental drop of a food container cap). And chronic SBD makes him a perma-loner anyways.
Crayola: anything goes, as long as it doesn't attack him. No shrimp (mmm shrimp)
Shiloh: new, and afraid of movement. Was in with aggressive fish at store, and the damage is done. I'll deem him a loner fish, because of that, and no snail because he shows he is a bully. XD
Ghengis Khan: a butterfly betta, beats himself up in stress. No fin nipping, a lot of head ramming. I think he'll be okay with snails.. Maybe shrimp. Too early to tell!
Reggie: was with aggressive fish in store and has no fins. No fish. I won't stress him :) he's super duper mellow so maybe snails... Possible shrimp!
I love how bettas are so diverse... I've noticed people askin if their particular betta would be okay with otos, or plecos, or shrimp, or snails... As you can see it depends.