usually these common analysis like determination moisture, fat, protein and ash ,,, are same for majority of food. you can use standard method and cite AOAC,
I attached a file for you, I hope it would useful for your research
You can use the aoac official methods for animal feed but with difference in sample preparations for fish meat and others , also you can found more information when you search about" Fish and Others marine products aoac" many procedure from worldwide and look for Manuals at FSSAI from india.