PhantomJug wrote on Apr 25^th, 2012 at 11:50pm:

Toss the raw chunks in the chowder to cook.  It doesn't take long . . . . 5-6 min maybe?  Northern seems to hold it's "shape" a little better.

PJ and MT have it right. Overcooked fish in chowder/soup turns to mush. Northern is good as it's firmer but you can still overcook it.
The cozie is a great way to make sure you don't overcook/burn your chowder.
You can buy one, or improvise in camp.
I take those big Reynolds Aluminum cooking bags for grilling trout. They'll hold a small chowder pot. Put your covered pot in bag, roll tight and use whatever you have handy for the insulation.
I use an old piece of foam Thermarest sleep pad that doubles as camp-seat.
Put pot on foam, fold over and use a couple of rocks to seal the ends. Works great.
If you don't make your own, Cache Lake makes a killer fish chowder thats even good sans fish.