I am SO sorry for your losses.
I know that we can even get attached to fish - especially when they attach themselves to us - and when we lose them it's a low blow, even though other people might think it's silly. (my brother had a gold fish Jaws that we got at a carnival and he lived for almost 11 years - we got him when I was really young so it was hard on me when he died).
Raccoons will attack a small animal if they're hungry enough, so please keep a very close eye on your little ones. Big hugs to you.
PS - I think there is a screen or something you can put over a fish pond to keep animals out. I don't remember where I heard about it though.