Heat butter in a large, deep skillet or pot over medium heat. Add the crab pieces and cook until golden on all sides. Remove and set aside.
Add the onion, carrot, and celery to the skillet. Sauté until softened, about 5 minutes. Stir in the jambalaya spice and garlic and cook for another minute.
Add the flour into the skillet and move it around until it clumps and turn brown or it starts to become aromatic. Quickly add the wine and using a whisk, break up the flour clumps. Add the chicken stock.
Return the crabs to the skillet, and add the potatoes and rice. Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for 20-25 minutes, stirring occasionally, until the rice is tender and the liquid is absorbed.
Finally add the shrimp, fish fillet pieces, bell pepper, and heavy cream. Gently mixing them into the rice. Cover and cook for another 15 minutes, or until the shrimp are pink and cooked through. Salt and pepper to your preference.