Hello sirs! Im about to get a baby black arowna about roughly 3-4" and im gonna put it in my L: 60" W: 24" H: 18" tank. My filtration is 4ft Mr. Aqua Trickle Filter 3 layers. Do i have to put a heater? Is it ok to put my 7" Flagtail together with my new baby black arowana? Thanks in advance!