Depends on what fish species, density, water temp and feed rate. Then dependencies on what type of aeration you are planing to use and how efficient it is at what depth.....

Key Points:
Diffusers may provide dissolved oxygen at 450grams/750watts/hour.
Generally active fish will consume 400-800 mg of oxygen/kg fish/hour.
Generally pond air pumps will provide 90 liters air/watt/hour

Example:
Lets assume you are stocking at 20kg per cube, 1meter deep, water temp is 25C and you are feeding 2% biomass per day. We are not including any bio filtration oxygen demands in this calculation and assumes this is an indoors recirc system. Air calculations are always rounded up!

Oxygen demand worst case:
Fish 20kg x 800mg = 16grams per hour
Feed 400grams (adds another kg) 1 x 800mg = 1gram per hour
Total 17 grams of oxygen consumed per hour.

Oxygen production:
450grams / our 17grams = 26
750watts / 26 = 30watts
30watts x 90 = 2700 liters per hour
2700/60minutes = 45 liters per minute
or 0.06 cubic meters per hour - Which would also equate to 3 cubic meters per hour per tonne. This changes with density per cube.

After all that assuming we find you may need a 45 liter per minute pond pump, however we must keep in mind we did not allow for any other bio loads on the system such as bacteria and the like, so lets throw in a 30% error margin and bump that pump up to 60 liters per minute air pump. You will need a bigger one if you also have a bio filter and other fun stuff. This is just for the fish tank.

have the 35w dc air compressor hooked up to a power fail switch and 5 x 120 amp hour deep cycle batteries which are charged by solar panels.
So far it works really well.