Were just trying to help here, allot of people with allot of experience with your same fish types over many years of experience, How big is your tank? I ask just because arowana are space hogs and picky when it comes to changes in space, the divider might make it worse, and people are a little anti ray attacking just because rays don't attack unless they are hungry usually, at least ive never seen different, and when they do its not for fins at all, as stated before they go for the gills and head, they are very smart, the markings on your fish is very much other fish like at the tail like get out of my space chase away and nip, rays don't have any reason to chase away a fish from the space as they own the tank or will get stressed and die being chased by others.