PBass and Arowana(jardini) growth rate?

so i am still in the planning stage of what fish i want to keep
when i get my tank build done. i am going to have rays and would like
to keep some pbass and an arowana also. If possible i would like to add
the pbass and arowana at the same time. i mainly see pbass @ 2-4" for
sale and arowana @ 6" for sale. what would be a good size to be able to
put these guys in the tank together so their growth rate is proportional
to each other and they dont try to eat one another? i have plenty tanks
if needed to grow one or both out to a suitable size. your thoughts and/
or personal experiences?

Thanks

Thanks, so then i should get the pbass and set them up in a grow out tank say like 3 months before i get the arowana. would it be safe to add them together to the main tank when they both hit around the 9" mark?

Well when the time comes around a black aro might be in the works.