Woo-hoo! Welcome, Argus. 
I’m not really creative at these things (or on time for these things, too bad decision has been made - but at least the choice is really good!), but our Betta just died round about the time that the OP went up, I would have suggested “Betty” in her honour (my daughter named “her” (although “she” looks more like pics I’ve seen of male fish, but my daughter wanted a female fish for her room). I loved the “Sid Fishious” choice, but I’m sure my 8 year old daughter wouldn’t get the ref.
And “Wanda” is my go-to name for fishes.