Preheat your oven to 400°F (200°C).
In a large pot over medium heat, combine the shrimp, crab meat, and fish fillets. Cook for about 3-4 minutes until the shrimp turns pink. Remove from heat and set aside.
Add chicken or seafood broth and heavy cream to the pot. Sprinkle in garlic powder, onion powder, dried thyme, salt, and pepper. Stir and bring to a gentle simmer.
Stir in frozen mixed vegetables and cooked seafood. Cook for an additional 5 minutes until heated through.
Stir constantly for about 5 more minutes until the mixture thickens slightly. Remove from heat.
In a separate bowl, combine Cheddar Bay Biscuit mix and milk. Stir until just combined.
Pour the seafood mixture into a large baking dish. Spoon the biscuit mixture over the top.