QUOTE(waterboy @ Feb 6 2008, 07:18 PM)

I used to have an aro pond back in asia. I kept aros in that pond for 5 years and they never attempt to jump, no fences or any cover. They actually go down when they get scared. Just for safety I'll recommend to put the fences, but the fence gets on the way when you look down in the pond. The more aros you put in the pond the less jumpy they become.
True if you startled them they would go down to get away, but the reason they attempt to jump is usually food flying by, so the risk of a jumper will always be present. a fence is your best bet to ensure safety