On the food network, they showed a guy who says he makes crabstock by boiling the shells in water for a few hours, how much flavor is that actually going to have?
Should you add clam broth like you do when making lobster stock?
crab stock has very strong flavour if made correctly.
i start by roasting the shells in an oven rather than in a pan.
then sweat down your miripoix with red chillies, red peppers, ginger, fennel and an orange.
deglaze with white wine, vermouth and brandy, add cold water and tomato paste and simmer very gently for a few hours.
if you have any fish bones such as halibut of monkfish or skate soak them for an hour in water to remove any blood
and add to the stock for the last 20 mins.
make a bouquet garni with star anise, coriander seeds, caraway seeds, fennel seeds or anything aromatic you can find and leave to infuse over night
i use this stock to make amazing risottos or reduce it by 90% and finish with cream for a rich sauce.
or if you really want to go crazy you can then cook crabs in the stock rather than in court boullion and get extra crab flavoured crabs and the stock will get stronger
Although you can't do this home it comes out great. Fill a 10 gal stockpot with lobster ,shrimp and crab shells(about 20 lobster carcasses) fill 3/4 with water and mirepoix, and herbs simmmer all day and strain at least twice you wind up with about 1 gal of stock extremely strong.
Crab stock and Fish stock are definitely two different things. The best fish stocks should retain a fresh ocean smell vs a fishy smell. So after you bring fish stock to a boil. Turn it down to a simmer but only for a short time.
Crab stocks / lobster stocks / shrimp stocks should be given time to bring its flavor and perfume to a complimenting mire poix, but you have to keep an eye on the caramelizing from the vegetables, etc. on the stove. You can extend the caramelizing time with very small amounts of water to prevent burning. I usually deglaze with white wine to "a sec" (almost dry) before adding water/chicken stock etc. to attain the level of flavor I am looking for. Bring stock to a boil then simmer will give you a clear pleasant tasting stock.