Gut and scale your fish.
Heat oil in a wok. Toast the fenugreek, cinnamon, corinder seeds, star anise, cumin seeds, mustard seeds for 1-2 minutes.
Add shallots, garlic, ginger, jalapenos, and tomatoes. Sautee for a minute.
Add curry powder and continue roasting for another minute.
Add coconut milk and bring to a boil.
Transfer to the slow cooker and cook for 4 hours on low.
Switch heat to high, add fish, and cook for another hour.
Season with fish sauce.