Honestly, 370 calories for a lauk portion is not that bad on its own. The fish itself, maybe 130g of ikan merah or tenggiri, is only around 140 calories and gives you a solid 24g of protein. The problem is the gravy. That 70g of santan-based kuah is packing 175 calories, more than the actual fish, and it soaks into everything on your plate. Worth flagging that these are ballpark estimates, because hard nutrition data for Malaysian home-style and hawker dishes is basically nonexistent. The real number could be 330 or it could be 420 depending on how heavy-handed the cook is with the coconut milk that day.
What actually moves the maths is how much gravy you take and whether the cook uses thick santan or the thinner stuff. A Negeri Sembilan-style masak lemak cili api version with extra santan can push to 430 calories for the same size portion. If you get kembong instead of a bigger fillet, the whole thing drops to around 280 calories because the portion is smaller and there is less gravy per serving. Practically speaking, if you are watching calories, ask for less kuah, eat the fish and leave some gravy in the tray. You can easily shave 50 to 80 calories just doing that, and you still get most of the flavour lah.