I know some people have fish in their frag tanks, I'm just curious if people use cycled rocks in their system so ammonia doesn't build up? I'm sure that would depend on how many fish you have in the system. I plan on only having one fish in roughly a 25 gallon system (total water volume), I am running a more than efficient skimmer for this tank as well running either a carbon bag/carbon reactor (any pos/negs on running one or the other?). Should I worry about ammonia build up etc?