wrote in
:

What kind of filter are you using? Do they seem to be breathing heavy?
If the oscar is getting hurt by the other one it is common for them to
lay on there sides, when they are hurt. If you have a good filter and
proper aeration I would do a water change asap. A great place to great
info on oscars and other fish is
http://www.cichlidfish.com/forumandchat.html very friendly people more
than willing to help out.

aquaclear 150 + a bubbler run filter.
I haven't seen any agressive behaviour, but that doesn't always mean
anything. :/

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