does the depth of a tank matter as much as the water volume and the quality of the water? Let’s say for a RTC or an arowana. Is tank depth as important as water volume? Say I had a tank that was 9 feet long by 8 feet wide by 12 inches deep would that be a big enough water for either of those fish? What if you were to add 100 gallons of sump space to that? All of this is a theoretical question.