stress problem

I agree with all the above.

I'm of the opinion that a 55 is not large enough for a pair of texas cichlids ( others may disagree ). There is enough room for the convicts and salvini to establish territories, and both are very defensive fish by nature. I think as they mature there will be some tough fights and you will end up with a salvini who lives behind the filter intake at the top of the tank.

I think that eventually you will be left with one pair of convicts in this tank. Until they fill it with more convicts of course.
 
AquariaCentral.com