I said that "I want to reach a point where I can skip the water change" pertaining to the current frequency of what I am doing, 30% water change daily.
In the past I used to change 30 to 40 percent water once every 10 days, but I had the parameters in check except for nitrate at around 20 to 40ppm.
Yes, I completely understand without water change the fish wont survive.
I have an Asian Arowana he is now 3 year old. When we got him he was 8 inches. Now he is over 2 feet in size. Initially he wss in a 125g but within a year the tank was too small for him. Now he is in a 220g. With my earlier 125g and 220g i never missed the werkly water change of 40%.
If you miss WC one week and then try to do a more larger water change after 2 weeks say 70% it may turn catastrophic for your Arowana. Any change in the new water mainly pH, temp etc will be stressful for the fish, they will stop eating and someimes die too.
So you will need to look for a larger tank very soon and upgrade your filtration for your Arowana if you plan to keep him longer and still continue with weekly water changes a must.