Kribs are tons of fun, and they are so beautiful! You can easily do them in a 20 gallon tank. I would prefer no tankmates with a pair, or maybe just some dither fish, that would hang around on the top, like zebra danio's. /They do well with plants, and prefer a cave as the spawning site. You can use inverted flower pots, or some of the spawning caves you see around.
They are great parents, at least for a couple of weeks, it is fun to watch. But as they fry get about two weeks old or so, it is probably best to move them to a fry rearing tank.