I've just bought 4 silver arowana babies (5'') for my tank. I'm aware of this DE syndrom and I'd like to avoid this problem. I've read a few theories about the root cause of it, mainly :
- too fat feeding
- head traumas when jumping against top covers
- unsufficient use of the "above water" vision
I've decided to put every chances by my (their) side and I've built a tank with a big "green wall" above the tank, without ceiling (but sliding doors, like on a terrarium). I feed them with crickets, earthworms, white fish, market shrimps, spiders and black flies... I'll try Hikari Jumbo Carnisticks as soon as I'll find a way to buy them in Europe...
I hope these actions will be sufficient to prevent the DE syndrom...
Let's wait and see in a few months (years ?)...