The chaps on Northcote Road are excellent and will take orders for you so you can book in advance, then pop down and pick up. From reading this thread it would seem that some of you feel conned by the quality. So I thought a few pointers on how to make sure you've got good fresh fish might be helpful:
Buying Whole Fish
Look for bright, clear eyes. The eyes are the window to a truly fresh fish. Basically they fade quickly into gray dullness. Dull-eyed fish may be safe to eat, but they are definitely past their prime and probably not best for a young family.
Does your fish shine? Does it look metallic and clean? If it has dulled or has discolored patches it's fairly marginal and I'd give it a miss too.
My favourite is giving fish a good smell. A fresh fish should smell like clean water, or a touch briny. Most fishmongers will let you have a whiff if you flutter your eyelashes a little.
If you can't get a whiff, then have a look at the gills. They should be a rich red. If the fish is old, they will turn the color of faded brick.
Look for vibrant flesh. All fish fade as they age. If the fillet still has skin, that skin should look pristine, shiny and metallic.
Smelling again but this time it is especially important.
If the fishmonger lets you, press the meat with your finger (in the supermarkets you can't do this - except on pre-packed stuff), if an indentation remains, then pass up the fish.
One last pointer, is to see if there is any liquid on the meat? If there is (and sometimes there is), just check that the liquid is clear, not milky. Sadly, milky liquid on a fillet is the first stage of rotton flesh.
I'm hoping some of that helps and should a door-to-door fishmonger arrive, you'll know what you're looking for. Oh and one last point, whatever they show you, if you pick it, make sure they wrap the piece you have pawed!