You're on the right path with the wood and leaves, just make sure they are free of contaminants before you use them. I never use any processed feed with any of my roaches. Dubia in particular just don't need the fish food in their diet. I have outlined in another post why using cat, dog and fish food is not good, not necessary and counterproductive especially if you are trying to raise the most nutritious feeders for your reptiles and arachnids. There are two factors to consider when choosing feed for roaches, or any other organism for that matter. One is nutritional factors verses anti-nutritional factors in each ingredient. Simply put, the good verses the bad and how those factors impact your roaches in the short and long term. The second is the nutritional needs of your roaches. Roaches have, to put it in common terms, symbiotic bacteria in their gut that scavenge nitrogen from the urea in their system. Roaches are protein synthesizing machines that do not need purine proteins in their diet.