Thank you all for the responses!
I may just cancel the order on the divider . . . I'm going to be backordering more nitrate test fluids anyway.
The divider was like $7, so maybe I'll get a couple sponge filters instead.
If I got the 1 betta, do you think I could have maybe 2 or 3 cories?
Would the betta try to attack the cories? If I do a betta and cories in the 10 gallon, who to add first? betta or cories? If the betta messed with them, I could always move the catfish to my other tank.
The tank is about to be empty because my incredibly reproductive guppies are going to a store in my area that I've been really pleased with their fish and cleanliness lately. I think the store will be able to sell them so they can rapidly reproduce as somebody else's problem! Never again will I buy guppies!
Anyway I'm really excited, I just want to make sure everything is planned out before I bring the betta home. Thanks!