Thank you everyone for your condolences.

When I say darting, he'll just shoot around the tank like a rubber ball, except he's not hitting anything. He goes so fast it's hard for me to even see him until he stops. He'll just shoot from one place to the other. He doesn't touch or rub against anything while doing this. Is M2 pretty common, as in easy to find? 'Cause I'd like to just go ahead and buy some to have it on hand.

Do you all think I should buy more tetras for the remaining one, Dopey? I know they're schooling fish, but I was also looking to maybe get a betta after buying a book about them and doing more research and they don't mix will with tetras do they?