oxygen level

Does my 120 gallon fish tank with a 6 month old Arowana have too much oxygen or is it good enough? ( there is also a bit of nano oxygen in the back.)

Hey guys! Since I’ve had my red arowana, it always likes to go to the waterfall area. I’m scared it might rip the fins or something or the tank has too little oxygen, What should I do?

I'm trying to find ways to make sure I have enough oxygen in the water in my new 240 gallon tank. I have 2 fx6's and was thinking of buying airstones, 2 aquaclear 110's or a powerhead to make sure the water moves. So I'm wondering how I am supposed to measure the oxygenation in my water and if...