I have a 400 gallon (1500 L) pond with two oscars, two tinfoil barbs and a 10" silver arowana. I've had this arowana for like 2 months and it hasn't try to jump out, yet.
It has plenty of room to swim around ( around 3 sqm) and if it want to jump out, it is possible to do so since water is few inches below the edge.
Please tell me if I still need to cover the pond with a net in this situation.