Tank Size?

I would get another serevum I have a green terror jack dempsey and a serevum all in a 55 gallon tank and they do pretty well together if i had enough room i would get another serevum I would go for a turquoise serevum very beautiful colors.
 
Here are my Oscars when they were in the 55 and now when they are in the 125.

Oscar1.JPG Oscars4.JPG
 
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