No Tetras, please. They might be okay, but I believe they need at least 15 gallons and a school fo 6 to shoal properly.
I reccomend Ghost Shrimp. I love thm! And in that great big tank, I doubt he would care, and even if he did they could hide.
I do not reccomend Cories. They need at least 20 gallons for a shoal of 4. Pygmys, though, are okay. You can get 6.
What about a snail? Funny little critters they are!
*2 Bettas (for now RIP Ryu) *2 Goldfish *9 Guppies *1 Gourami *2 Chinchillas *2 Budgies *2 Dwarf Frogs *1 Dog *1 Cat *2 Hermit Crabs *2 3gs *1 10g *1 Pond *2 2gs