from my friend paul, who is a serious, linux-using fishmonger:

“well. couple things to keep in mind. while i’m in favor of small local
shops in general, some times they have to charge *more* for fish
because they can’t consolidate their buying like a larger company. we
can throw our weight around a little and get deals on stuff that’s
abundant or sometimes secure lots of fish that are difficult to find.

frequently the downside is that larger companies can’t be as quick to
respond which is important in seafood. there have been times when i’ve
seen fish in other shops that we can’t get because the fishery can’t
supply enough for the whole region. with good regional buying and some
autonomy (for purchasing) at the store level this tends to be less of
an issue.

larger companies also tend to be worse in terms of service, but i
think we do a good job of avoiding that trap. i’m talking about *real*
service beyond the “hi how are you” and “have a nice day” kind of
thing. being able to articulate why it might be *better* to spend an
extra buck or two because of cleanliness, sustainability, catch
methods, freshness or what have you is vital in seafood. a lot of
people assume that fish is fish is fish and that isn’t always the
case. i can’t tell you how many people will call and tell me that a
particular piece of fish is no good, then when pressed admit that not
only did they buy it somewhere else but it was frozen, treated with
who knows what, and purchased out of a self-service cooler or freezer
with no service counter.

here’s my advice. find a guy (or girl) who you trust in a shop near
your house. they should have similar tastes to you in seafood– lean
vs oily, meaty vs flaky, strong vs mild &c. they should not be afraid
to send you somewhere else when they can’t get what you want, which i
do for customers who are looking for squid ink, crawfish, shrimp
paste, live crab and so forth. they can be the owner/manager but they
don’t have to be and sometimes it’s better if they aren’t. you should
be able to ask them what they like on any given day and feel like
they’re telling you what they like and not what they’re heavy on,
although sometimes it can be the same thing. never ask them if the
item in question “came that day”, not only does that imply second
guessing their opinion (which you should trust) but a lot of times it
doesn’t matter when a batch of fish *arrives* in the shop, as long as
it’s good. more on that later if you want.

they should be ready to convert decimal pounds to grams for anyone
with an accent or who asks. they should be willing to talk about
seasonality and availability, at length if need be. they should know
both the market names and FAO/AFS names for all fish they carry, and
ideally use the most “correct” name in their signage and speech.
things like rock cod/rockfish, butterfish/sablefish, ahi/yellowfin, &c
fall into this last category. bonus points for binomial/latin names ie
sebastes nebulosus. they should be able to fillet, butterfly, steak,
scale, gut, j-cut, c-cut, and pinbone where appropriate, although time
constraints may prevent them from doing so on the spot for you. they
should at least be able to describe or demonstrate how to shuck, peel,
clean and devein so that you can do so with your oysters, shrimp, and
squid respectively provided they don’t have options that are already
done.

shop frequently. do not shop hungry. pay attention to seasonality and
location. do not decide on recipes involving produce, seafood (except
shrimp which are almost always frozen anyway), or cheese before you
have seen/felt/smelt/sampled/looked at the product– see alice waters.
keep in mind that price is frequently determined by availability with
perishable items– if they’re catching a lot of white seabass the
price is frequently lower than it would be otherwise. do not be afraid
to make mistakes. do not be afraid to gut, clean, or shuck things
yourself, as certain items are much better if they are processed right
before cooking or consumption. do not plan a big elaborate meal for
someone you are trying to impress around an item that you are not
certain is available or in season, or an item you have never attempted
to cook before.

fisheries that tend to be big in southern california include
california halibut, smelt, squid, sardines, corvina or white seabass,
farmed striped bass, and albacore tuna. this is by no means an
exhaustive list– your seafood guy should be able to list five more at
minimum. you can call ports seafood in the late afternoon or evening
for a prerecorded message detailing what’s happening in various parts
of the world including southern california– 415 593 8080.

if you ever get a piece of fish that is less than perfect you should
call your seafood guy or the shop where he works to get a refund.
their first response should be to offer you credit or a refund,
followed by appreciating you for calling and alerting them to a
potential issue. they may ask additional details but the tone and
spirit should be inquisitive rather than confrontational. do not call
and ask about a piece of fish you purchased somewhere else. by calling
in you are actually doing them and other customers a favor and they
should recognize that as long as you aren’t being belligerent or nasty.”