Amplang is one of those Sabahan snacks that sounds innocent because it has fish in it, but bro, the fish is almost a side note. The real calorie driver here is the sago starch base and the frying oil absorbed during cooking. Out of 135 calories per 25g handful, roughly 65 of them are straight from oil. The fish content is only about 5g per serving, giving you a measly 15 calories of actual protein. If you see it being sold at Kota Kinabalu airport or a pasar malam stall, it's genuinely delicious and worth trying, especially the ikan tenggiri (Spanish mackerel) version. Just be honest with yourself about the portion. These numbers are a ballpark estimate by the way, because proper lab data for amplang is thin and most packages round off or differ by brand.
What actually moves the maths is how much you eat in one sitting. A small 25g handful is 135 calories but a typical 100g snacking session (which is easy to hit while watching TV) is around 540 calories, roughly the same as a full plate of nasi goreng. The udang (shrimp) variant runs slightly higher at about 140 calories per 25g. There is no real lower-calorie way to prepare amplang since the deep frying is baked into the product itself. Your best move is to portion it out before you start eating, put the bag away, and pair it with something filling like a cup of black coffee or tea rather than snacking from an open packet.