powerliftintexa, I've done the RBT/Tilapia combo for year round forage, and here are my thoughts based on personal experience. Mozambique tilapia can be safely stocked at 65 degrees. There probably won't be algae in your new pond, and if you do have it, it won't be enough to successfully feed the tilapia. Because of that, you'll need to supplement their food with fish food, which will also feed the catfish. The catfish growth will probably out pace the tilapia growth, which means that you'll be feeding fish food to the catfish anyway.
Stocking RBT has it's issues also. Texas hatcheries make runs up north to pick up RBT, and you may be required to put in an order to even get the RBT at the size you want. TX hatcheries don't want to keep them any longer than they have to, or feed them for any length of time. A variable will also be what your water temp is in relation to the pickup date of the RBT. If they aren't close, you could potentially kill the newly stocked RBT. Unfortunately, I lost around $400 worth of beautiful RBT over that same issue. Most likely, there will be a gap in the tilapia fall life span and the RBT stocking, so again, you'll be feeding the catfish pellets. RBT lifespan "should" overlap the spring stocking of Tilapia, so that is a plus. Snipe had mentioned your pond water being mixed, and that's the unknown variable. If catfish keep the pond water stirred up looking for food, then the RBT won't excel. RBT need clear oxygenated, or low biomass loaded water.
Bottom line is that at some point in the year, you will need to supplement the catfish's food anyway. Prices for Tilapia and RBT are also rapidly rising like everything else, so the financial aspect is something to consider. If you do want to try the RBT/Tilapia mix in a 70X30 pond, then go slowly, and ease into it. IIRC, catfish are the #1 fish sold by TX hatcheries, and I'd be willing to bet that most of those that are fed, are pellet fed.
