using fish emulsion for intial cycling

Why doesn't anybody use fish emulsion ( Liquid fish fertilizer) for initial cycling of systems. I know from experience that it gives of lots of ammonia when you use it in compost " Teas" was just wondering since pure ammonia is hard to come by in some areas. I have no qualms about using " Hummonnia" and sea weed but I'm trying to learn as much as possible before I start my own system.