oxygen

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.)

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...

Hi everyone im new to this forum. I would appreciate if someone could help me out. My brother is starting a new aquarium in his room it's a 55 gallon tank, that is 4 feet long, and he is planning on putting 25 one inch demesoni in there. The tank is in his bedroom so he wants it to be as quiet...