Pat the fish dry, cut into 2-3 inch chunks, season with lime juice, salt, and pepper, and set aside.
Dice the onion, chop the scallions, mince the garlic, and cut the pumpkin, potatoes, carrots, and okra into uniform pieces.
Heat the coconut oil in a large Dutch oven over medium heat. Sauté the onion and scallions for 5-7 minutes until softened. Add the garlic, thyme, and allspice and cook for 1-2 minutes until fragrant.
Pour in the fish stock and water. Add the pumpkin, potatoes, and carrots. Nestle the whole scotch bonnet pepper into the broth, season with salt and pepper, and bring to a boil. Reduce heat and simmer for 15-20 minutes until vegetables are just fork-tender.
Add the sliced okra to the pot and continue simmering for 5 more minutes to slightly thicken the broth.
Gently add the seasoned fish chunks to the pot, nestling them into the broth. Cover partially and simmer for 8-10 minutes until the fish is opaque and flakes easily.
Remove the scotch bonnet pepper, and either discard it for a milder soup or pierce it for extra heat. Stir in the lime juice and discard the whole thyme sprigs. Adjust seasoning to taste.
Ladle the soup into deep bowls, garnish with fresh cilantro or parsley, and serve immediately with crusty bread or rice on the side.