Mix the chilli powder, salt, garlic, cumin, turmeric, tandoori masala and lemon juice to form a paste. This will be the marinade for the fish. Give it a taste to check that the salt is ok. It should be a bit on the salty side, but not too much.
Rub this onto the filleted pieces. Make sure you wear gloves whilst doing this otherwise your hands will burn from the chilli powder.
Refrugerate the fish in this marinade for at least 6 hours (keep it covered). I normally get a big batch of fish, marinate it like this and freeze for up to a month.
Now heat some oil in a frying pan preferably non-stick, then fry your fish fillets! Do not move them around in the oil at first. If you try and turn the piece and it feels like its stuck, let it fry for a minute or two more and it should release on its own. Fry both sides until golden brown.
Remove and drain excess oil, then blot on tissue paper. Serve with sliced potatoes in tomato gravy, spinach and rice or rotis or, if you like African food like I do, you may serve it with ugali/sima...an E/African dish made out of maize-meal