In a heavy-bottomed pot, heat oil on medium-high. Add sausage, carrot, onion, celery, pepper and garlic; sauté for 5 minutes.
Remove pot from stove, sprinkle in flour and mix well. Add chicken stock and stir well to prevent lumps from forming. Return to stove on medium heat and add tomato, salt and catfish. Simmer for 30 minutes.
Pour piping hot into a large, insulated food container. On the ice, serve in bowls with bread slices.