There are many different ways to grow food using aquaponics. You also have several fish and crawfish species that are used as a food source in your prepper aquaponics system. I am currently using crawfish in one of my 55 gallon tanks that circulates into my pepper plants. The crawfish I use were actually caught from my local creek and ponds. Nothing fancy, but they do the job. Eventually I will upgrade to a more edible species like the Australian Red Claw. They get huge and can easily be used as a regular food source since they mature in 6-12 months. Here is a link to the Amazon store that sell Red Claws. I have been researching Live Aquaponics and they are the best online sellers for these Australian Red Claw crayfish.
Channel Catfish is another option for prepper aquaponics. They grow quick and are tolerant to most water conditions. Channel catfish along with tilapia are one of the main food sources in aquaponics systems throughout the US. Unlike tilapia, catfish will still continue to grow in lower temperatures. Catfish are easy to feed also, they like minnows, worms, crickets, and pellets that land on the bottom or tap of the tank. When feeding a commercial feed on a regular basis, their meat will be as clean, white, and as well marbled. There are local breeders in every state that offer catfish fingerlings. You can also buy them online year round. I found several stores selling catfish, all of them have a great reputation so I have no problem recommending several options based off the location you live in the states.
I am sure there are more great sellers online, please send me links if you have had a good experience with any online sellers who should be added to this list.