That's good to hear that the cory will be moved and hopefully will get some buddies
I dunno what it is with bettas and cories, but it seems they enjoy eachother!
I had a female betta in our community tank that used to always swim and hang out with the cories. She would even rest with them.
Bad photo, but you can see her w/ the cories

She was such a sweet betta
Anywho, very cute tank. The gravel color really isn't my taste though heh.