Out of the three (actually four,but the first is little used) rouxs used, Creole cooks mostly use light or "Blond" in gumbos. Roux is just a 1:1 mixture of a fat or oil and flour, which is cooked in a heavy pan. The longer the roux is cooked the darker it becomes. Therefore, you'll find the blond roux cooked only about 5 minutes or so. The others are medium and dark and do take a lot longer to cook down... Cajuns (in and around Houma, Louisiana) prefer the smoky dark roux...