To stop your masala coating from sticking to the pan when frying fish, make sure the fish is super dry, coat it thoroughly, use enough hot oil, and avoid overcrowding the pan.
A common culprit behind masala sticking is either too much moisture on the fish or not enough hot oil. First things first: grab those paper towels and pat your fish completely dry before you even think about adding the masala. Any extra moisture will turn into steam and can actually lift the coating right off. Next, apply your masala mixture evenly, ensuring it really sticks. If your masala has a bit of cornstarch or rice flour in it, that really helps with adhesion. Now for the heat: warm your pan over medium-high heat and add enough oil to create a thin layer that covers the bottom. The oil needs to be hot enough to immediately sear the coating when the fish goes in. If the oil isn't hot enough, the coating has time to absorb oil and, you guessed it, stick. Lastly, don't cram too many pieces of fish into the pan; this drops the oil temperature and releases steam, both of which contribute to sticking.
If your masala tends to be a bit sticky, try a very light dusting of rice flour or semolina over the coated fish just before frying. It creates an extra barrier that works wonders!