If you are getting a 55 gallon and you are talking about a pair of either of the following I think you would be best off getting a pair of firemouth. I say this because they are great fish and somewhat easy to breed. Also if you are trying to get a pair in a 55 I would say IMO that the firemouth pair would be better off in that size tank than the JD pair. A JD pair could work in a 55, but I would see that to be a minimum size tank for this pair. So the future 55 gallon is more ideal IMO for the firemouths than the JD's. Good luck.