afraid so, but show me a large silver in an aquarium without it in at least one eye...
this might help copy and pasted from yahoo answers
The whole issues with fatty deposits beneath the eyes coming from feeder fish has not been proven yet. Or even the fact that these fatty deposits cause droop eye.
There is a few reasons that can cause droop eye and ill tell you now how to get rid of it properly.
Causes being looked at.
1. Not all arowanas get drop eye so it might be down to genetics in the fish.
2. Your fish could be looking down alot and his eyes are starting to pull or droop. Usually due to looking at his own reflection.
3. It might be his diet. But this has not been proven at all.
4. Natural wild arowanas don't seem to have problems with droop eye so it might be down to the tank environment.
These 4 issues are what is being looked into and researched at the minute. There is no Evidence leaning towards away, so i don't know where the other answers are getting there information from.
Right now to the good part. I have had to deal with arowanas with droop eye over the years and i'll tell you how to help your arowana.
1. Make sure that the bottom of your tank is covered in stones, to cut down on reflection's. Arowanas are noisy and will watch whatever moves even there own reflection.
2. Cover the sides of your tank with paper or card board so that the arowana has nothing to see and will be forced to look up. This will help to reverse the drooped eye.
3. Place 2 or 3 ping pong balls on the surface of the water. As they float around the arowana will watch the balls and his eyes will be drawn up wards.
Over the years of dealing with arowanas i have come across only 3 arowanas with droop eye and i have cured it using these methods. They do work.
Hope this helps you and good luck with your fish.If you use this few tips you will start to see results in a few weeks. You just didnt say how bad the droop eye is right now.
BTW here is an article from a respected arowana breeder and dealer that i know.
http://ezinearticles.com/?Arowana-Fish--...