One of my goldfish would try to almost jump out of the water under the waterfall. It's head would come out of the water for a feww seconds.It dosen't always do this though.Is is normal??smilie

I've been thru this. :D If there is enough of oxygen, then they're probably playing. One of our goldfish would jump the 10 inches to LAND in the waterfall pond. They all went to the bigger pond with a bigger edge around it. No more jumping out, but they do still play 'whale and dolphin' once in awhile. When I first turned on the waterfall think 6 little FLIPPERS...scared the crap out of me, didn't know what was going on. lol

As SadieMay said, unless there's low oxygen, the fish most likely are just having fun. Most fish sometimes try to swim or jump upstream. My fish hang by the waterfall when I'm cleaning it off to catch bugs.