Ikan stim is steamed whole fish, typically siakap (barramundi) or ikan merah (red snapper), covered in a light sauce and finished with aromatics like ginger, chili, garlic, and coriander. It is a staple at Chinese kopitiams and plenty of Malay restaurants. At roughly 310 calories for the whole fish, about 216 of those calories come from the fish flesh itself. The sauce adds around 66 calories, mostly from the sesame oil and a bit of palm sugar. The aromatics are basically calorie noise. So honestly, the fish is just a really good deal, protein per calorie is one of the best you will find anywhere on a Malaysian menu. Fair warning though: these numbers are a ballpark estimate. Reliable lab data for steamed fish as cooked in Malaysian hawker settings is thin, and sauce quantities vary a lot between cooks.
What actually moves the number is the sauce. A heavier hand with sesame oil or more palm sugar can push the sauce component up by 30 to 50 calories without you noticing. The Thai-style stim limau version stays around 310 calories because the lime and fish sauce base is fairly light. The ginger steam version (stim halia) comes in a bit lower at 280 calories because it skips the sugar and heavier aromatics. If someone adds coconut milk to the sauce, which does happen in some Malay-style preparations, you are looking at 390 calories instead. Also worth noting: the edible flesh on a mid-size fish is roughly 200g out of the 280g total served. If you order a bigger fish, scale the numbers up accordingly.