Ok, I won’t do any arowana. I’ll go with some bichirs and maybe a spotter gar and cichlids, I’ll do 50 percent water changes every 9 days. Or every Sunday if that’s what it comes to.
Start out with some cichlids and see what it takes with them. Then you can jump on to larger fish. The larger the fish is the more maintenence it is. And the more filtration you will need. On my 3200L tank i run an beadfilter thats supposed to handle 36000L koipond and in addition to that i run two large showerfilters with roughly 80L of biomedia and an protein skimmer.