If you eat some undercooked catfish you could potentially get sick and get Salmonella and Vibrio vulnificus from the catfish or other fish that is not properly cooked.
I always make sure any catfish or any other types of fish I eat is well cooked before eating it to avoid getting any sickness from it.
When catfish is fully cooked the catfish becomes opaque and flakes which is one way to tell when the catfish if fully cooked and ready to eat.
You can also use a fork to tell if the fish is cooked fully and ready to eat.
Take a fork and poke the tines of the fork into the thickest portion of the fish at a 45-degree angle and then gently twist the fork and pull up some of the fish.
If the catfish is not fully cooked it will resist flaking and be translucent.