Keep an eye on them, unless you have a m-f pair, as they mature there is a good chance they will become enemies.
You didn't say what type of filter you are thinking about. Because JD's are messy eaters I would go with a filter that has a gph
rating of at least triple the tank size, if not more. And that is regardless of which type you choose. I like the fluval and the rena canisters. I currently run the older model penguin HOB
's and I like them, unfortunately you can't purchase those with that design any longer.