I kept mine in 10 gallons. They can do fine in a 5, but I find them to be much happier in a 10. Also, make sure whatever decor you get is smooth! You don't want to rip their fins. Silk plants are what I used, Petco has nice ones. Also get a quality food, I used Omega One flakes.
They need the standard fish stuff, heater, filter, etc. The only piece of equipment I skip is an air pump. Since they have what's called a labyrinth organ, they take air from the surface of the water.
I got my first from Petsmart, and then my next 3 from Petco. Generally they did okay. First one lived 2 years, second lived 1 year, and my 3rd and 4th only lived a few months and died 2 days apart. Maybe I would have had better luck if I had gotten them at the LFS.
I'll tag
@finchly , she knows tons of fish stuff!