Peel and cut up your tuber of yam into small chunks, rinse a few times till clean before transferring to a large pot.
Add in your chopped onion, season with a tsp of fish bouillon and some salt, add the 4 cups of water and cook for 30 mins.
Meanwhile, blend together your red bell peppers, scotch bonnets and 1 onion.
Heat up a large skillet, add in your palm oil and let it heat up for 2 mins before going in with the blended pepper mix.
Allow the mix fry for 15 mins making sure to stir intermittently to prevent burning.
Add in the deboned catfish and ground shrimp, season with salt and fish bouillon.
Add your fried pepper sauce to the boiling yams, at this point, the water in the yams should be significantly reduced, let it combine well while still cooking.
When the yam pieces are soft enough (you can use a fork to poke a piece to be sure), add in your chopped shrimp let it cook for another 5 mins.
Use a wooden spoon to break down the yam pieces leaving only few chunks. You should end up with a semi-pureed pot of yam pottage.