There are so many methods available for preserving the Bombay duck. Since this fish is regional based very little scope for chilled marketing. You can think about solar tends, Mechanical dryers for drying the fish in rainy seasons. Here i suggest to focus for cleaned fish in to split pieces and dry. so, more money can be gained. Other things like protein powder, protein hydrolysates etc also good options. The main constraint is that it required more investment and infrastructure facilities
Bombay duck is most popular as salted and sun dried fish and also as canned fish(for export).
Sun drying is obviously restricted in rainy season but mechanical drying using cabinet dryer/tray dryer or may be fluidised bed dryer is a good option though the cost will be little higher as compared to conventional sun drying as the latter is still adopted on very large scale in India.
Processing Bombay duck having such a great commercial value for processing it into protein powder/protein concentrate/protein isolate cannot be considered as a wise idea.
I cannot fully agree with the above comment. Protein powder is one of the high demand product in nutraceutical market. Compared with other protein sources fish protein is superior and more preferred in functional food sector. In India, still people are selling Bombay duck in traditional sundried form and its value realization is comparatively lower