Finely dice the onion. Wash the peppers, cut in half, core and cut into strips. Peel and finely dice celeriac. Wash and dice the tomatoes.
In a saucepan, sauté the onion until light yellow, add the vegetables and fry over a medium heat for 5 minutes. Add the vegetable stock, creme fraiche and paprika powder. Season with salt and cover and simmer for 20 minutes over low heat, stirring occasionally.
Salt and pepper the catfish fillet and cut into bite-sized pieces.
Add to the vegetables. Cover and leave to stand on the switched off hotplate for 10 minutes.
Season the goulash with salt and a pinch of cayenne pepper (chilli).