oscars sizes

Question
we just got another oscar and this one is bigger and has less orange stripes why is that?both the fish open there mouths at one another what does that mean?and why do they shake there body?

Answer
Trish,
All fish come in different shapes, sizes and colors. One might be older than the other. One might be male the other female. If one of the Oscars were in the tank before the other, the one that has been there the longest, is letting the other know that he/she is the top fish and that is normal. This should all calm down in a few days when they both have had time to get used to each other.