No bolivans in anything less than a 20 long. Angels, since you need a group generally, nothing less than a 38gal, preferably a 55gal, its much better. I would even be weary of putting a pair of German blues (who got their name from where they were originally exported to for mass breeding, they're actually native to South America, and are mostly now mass bred in asia) in your 10gal, from my own extensive personal expirience with them, a 20 long should be the minimum, especially for new pairs. Yes they will eat little guppies, like just about everything else under the sun.