I have 10 Clown Killifish in my 55g nano fish tank. I've actually been thinking about getting a pair of Aussie Gold's. I have Northobranchius Rachovii in my 220g and I think they would look and do well with the Auggies. Rachovii males can be quite aggressive with males of their own species so be sure if you would add more than one pair or trio that they are in a good sized planted tank. I've never kept more than one type of killi in the same family together so I don't know if it would work or not.