I would definitely put a knife with the aro.
As to how many knives, there are a lot, all the Clowns, Royal Clowns, Mekong, Bronze ( Notopterids that go between 2 and 4 feet, for the Mekong ), then you have the african knives, up to 8/ 10 inches, also beautifull, brownish without a fin in the back, you have the south americans, starting withe the black ghost, and then, beyond all the most known ones, you have loads of fantastic knives, such as the Aba Aba, the glass knives and all those marvellous odballs you see on pix (at least around here, you only get to see them in pix...)
Miguel