I've been looking into a lot about DE, however, I have not notice/read (Maybe just me) that it might be caused by our lighting system where it's too bright for our Arowanas to look up, so they must look down to prevent the glare that's IN THEIR FACE. I am raising a couple of baby Arowanas in my 150 gallon for a while with very dim lighting to see if this theory prevents DE or not. What do you think? If this has been discussed before, then, oops. I'm still going to go with lower lighting for my Aro tank.