1. Mix catfish pieces, lime juice and red pepper flakes in a shallow dish.
2. Heat sesame oil in a large saucepan over medium-high heat. Add onion, celery, cabbage, ginger and garlic and saute for 1 minute. Sprinkle with curry powder and celery salt. Reduce heat to medium and saute for 5 minutes or until onion is tender.
3. Add chicken stock; bring to a boil over high heat. Stir in catfish mixture. Bring to another boil, reduce heat to medium and season with soy sauce. Simmer for 3 minutes or until catfish flakes easily when tested with fork.
4. Place mounds of rice in the center of large soup bowls. Ladle the soup over rice. Sprinkle with the chopped cilantro or celery leaves and serve.