You can also buy concentrated stock packages and just bring them to a simmer with however much water you want to use for the consistency. I basically never bother with doing it from scratch these days.
Where are these concentrated stock packages? I've had better than bullion and added gelatin to that, and I think I've seen heinz demi, but what concentrate stock packages to you have available?
Asian food stores have lots of seafood related stock that is difficult to locate elsewhere. For instance, I'll use shrimp paste sourced from Asian food stores when making shrimp étouffée.