Cook couscous according to package directions. The "pearl" version usually takes about 8 - 10 minutes to cook.
In a small bowl combine the cumin, chili powder, coriander and a pinch of salt & pepper. Evenly rub the spice mixture on all sides of the fish and set aside (in the fridge if you’d like).
Peel, core and dice the mango. We use a mango corer at our house. Chop the cilantro into small pieces. Put the mango, cilantro, and lime juice together in a medium-sized bowl and set aside.
Heat the butter in a large sauté pan over medium heat. Add the seasoned fish to the pan and cook on both sides until it’s white all the way through. For thinner pieces this might only take a few minutes.
Once the couscous is done transfer it to the bowl with the mango, cilantro, and lime. Add ¼ teaspoon salt and mix together thoroughly.
Divide the couscous mixture evenly among plates. Top with pieces of fish and extra pieces of cilantro. Serve warm with a salad or vegetable on the side and enjoy!