Bring 3 cups water to a boil in a large skillet; add catfish, and return to a boil. Cover, reduce heat, and simmer 5 minutes or until fish flakes easily with a fork. Remove from skillet; drain well, and cool slightly. Flake fish with a fork.
Stir together cream cheese and next 4 ingredients until blended. Stir in onion. Spread cream cheese mixture in a shallow dish. Add chili sauce, and top with pieces of fish. Garnish, if desired. Serve with crackers.