I have 2 aquariums one is in my bedroom with my 3 6" oscars and the other is in the room next to mine with 4 babies. I guess it was around a week ago I was awaken from a deep sleep with a 'BAM' in the other room. I realize these are sometimes noisey fish so I went back to sleep and about 15 minutes later heard it again. I went to check it out and my lemon was on its side near the top like it had jumped and hit the top. I thought he was really hurt so I reached my hand in and touched him for a moment before he dashed to the bottom. The same exact thing happend last night with the same fish. At fisrt I thought maybe something was sending electric shocks but the volt meter turned up nothing and all water readings are ok. My guess is something spooked him and he is jumping out and hitting the top of the aquarium but I am open to any other ideas?

I remember my Oscars doing that. Apart from buying a hard hat for your Oscar, I don't think you can stop them doing it. Just make sure that the condensation cover is completely clean so they can't see anything, I think sometimes they see things and lunge at them

A hard hat for an O what a great idea maybe we could do body armor.

I have noticed with mine that if there is a little algae build up on the cover he'll go after it. Keeping the cover clean is an excellent idea.

Mine do the same thing and theres nothing i can do bout it.

my one O sleeps on his side at the top of the tank and looks dead too oscars do weird things ive heard of people that put a kind of a netting cover under the condensation plates to stop their fish from hurting themselfs

Yeah my o does the same thing,but only when lights are on.
He looks like he sees something on the waters surface and darts up and `BANGS` into the condensation cover.
The cover is about 2 inches above the surface.....Makes you jump sometimes:)

Mine has stopped banging around quite so much, but it was nearly a daily thing.

He gained lots of nasty looking chunks missing from his head, scraped scales off, and generally making himself look like a veteran of a one man war.

Lately, he has been acting odd again ... Yesterday he freaked out and went from top to bottom a few times ... almost like he has anxiety attacks

I recall a time or two he thrashed around really bad and floated at the top, I thought he killed himself, but he was just pouting from guaranteed pain of his actions. Had the surface of the water looking like a lake during a storm.

He also use to try to attack something on the lid ... never could figure it out. One spot could have been the orange sticker on the top frame, but another spot I couldn't find anything of interest.

Hope yours stops soon so as not to worry you any more.