I'm getting a 170g tank soon and I've come across two different fish I'd like to house with the oscar i'm set on getting. I was think either 3-4 severums - or - 5-6 Bala sharks. I'd be getting them all (including the oscar) as young fish to allow them to grow together. Anyone's opinion or advice if you've ever had this combo of fish or know anything, would be appreciated. Thanks!