Season catfish and shrimp with garlic powder, paprika, Cajun seasoning, and curry powder; set aside in a bowl.

Heat a 6-quart pot over medium heat for 2 minutes; add olive oil. Add corn, bok choy, onion, bell pepper, serrano pepper, and garlic. Stir-fry until onion becomes tender, about 5 minutes. Add tomatoes and cook for 5 minutes. Pour in water and bring to a boil. Reduce heat to medium-low, cover, and cook for 15 minutes.

Add catfish and shrimp to the soup. Cover and cook until flesh is opaque, 6 to 7 minutes more. Garnish soup with cilantro.