When keeping central american cichlids does it matter whether you use sand or gravel as the substrate? I've always used gravel but fancy using sand as i'm not using under gravel filters?

I honestly think it would not really matter that much to the fish.

i prefer sand as a substrate but like glaive said, i don't think the fish care much either way.:D

Again, it may depend on the species...South American "Earth Eaters" for example, certainly prefer sand...what Central American Species are you thinking of keeping?

Just be cautious using sand or really fine gravels with some of the larger CA's that tend to be big digger/spitters. It's a good idea to be carefull to position your filter intakes in spots that won't get too much intake if the tank is stirred up as it can be harsh on filter impellers and damage some filters.