I have been taught that to remove the yellow fat fron catfish particularly channel cats put them in boiling water. Bring a pan of water to a rolling boil and drop the fillets in for 2 minutes. 2 minutes only, we don't want to cook them just release the fat. Remove the fillets from the boiling water after 2 minurs then fry as normal. I had heard of this idea several times so i tried it. It works every time. The yellow color is there but the foul taste is gone.
You also need to trim all the red meat off the fillets too. This helps immensely to improve the flavor. I would not eat channels before the boiling water trick. You will see a thin layer of yellow fat floating on top of the water after you have boiled several fillets so you know it is working.