Brown rice and seafood gumbo

Name: Brown rice and seafood gumbo
Ingredients: ¼ cup olive oil; 1 brown onion, diced; 1 green capsicum, diced; 2 stalks celery, diced; 3 cloves garlic, roughly chopped; 2 tbsp tomato paste; ½ tsp each smoked paprika, cumin and dried thyme; ¼ tsp cayenne pepper; 2 bay leaves; 1 tsp salt; 1 cup brown rice; 1 can (400g) whole peeled tomatoes; 1½ litres unsalted vegetable, fish or chicken stock; 300g okra, trimmed and cut into 2cm slices; 500g monkfish fillets, cut into 5cm pieces; 500g green king prawns, peeled and de-veined; 500g mussels, scrubbed and de-bearded; 25g butter