First of all, clean the seafood shells with cold water toremove the dirt or particles.
In a large pot, warm a tablespoon of oil over medium heat. Add the seafood shells and cook them stirring occasionally until turned pink and fragrant, it may take around 5 minutes.
Add the chopped carrots, onion, celery and garlic in the pot. Cook by stirring occasionally until the veggies are softened, it may take around 5 minutes.
Pour in the water and include black peppercorns, bay leaf or any other fresh herb as per your liking.
Warm the mixture until boiling. Lower down the heat and let it simmer gently for around an hour. Remove the foam or impurities that float on the surface.
Once simmer, pour the mixture through a cheesecloth or a finesieve into a container discarding the bits behind. Before storing, let the seafood stock cool completely for up to 3 days.
You can consider this seafood liquid as a base for stews, risottos, stews or any other seafood flavored dish.