Add the canola oil to a large stock pot; sauté the onion, carrots, celery, lemongrass, ginger and garlic until brown, about 5 minutes.
Add the coconut milk, curry paste and honey. Simmer for 30 minutes then strain out and discard the vegetables, reserving the sauce.
Add the mahi mahi, shrimp, scallops, clams and mussels to the curry sauce and season with salt and pepper to taste.
Simmer about 20 minutes. Serve with a slice of lime and a bowl of hot and steamy sticky rice.