Perhaps this can help?
FISH, FISH AND MORE FISH
Having a lot of time this summer, I have been spending a lot of time at library and reading at home and experimenting. I found many great articles, and books on fish . Here is a condensation of all of them, and the results of some things I tried.
Perhaps the most important things in securing and getting quality fish is their source. The waters that they come from should be clean and flowing. The fish monger trustworthy and honest.
The other important factors is the holding and storage of fish. Some are different then others with assorted shelf lives.
EXAMPLE Fatty saltwater fish like salmon ,herring, mackerel, sardines will hold about a week.. Lean cold water species like cod, sole, tuna, trout roughly 2 weeks, lean warm water varieties like snapper, catfish, carp ,tilapia , and mullet about 3 weeks.
All of the above are based on time of catch..
The most important thing is correct refrigeration. Most things we consume a 38 to 40 degree refrigerator is adequate, not so fish. It must be on ice, and not ice cubes or large slabs of ice, but crushed ice or slurry ice. Fish last two times longer in a 32' slurry then in a 40-45' fridge. It should also be run under fresh cold water and let dry then wrapped . The reasoning behind the water is the additional handling by so many from the source only makes it more prone to bacteria buildup on the outer exposed sections. This combined with proper airtight if possible wrapping ,and chilling slows the enzymes and bacteria down that attacks the fish.
Notice I say airtight, as this stops the fish from getting immersed or touched by water from ice melting. which leeches flavor from the fish. Beware shellfish, do not buy it already thawed as you do not know how long it has been thawed. If any odor at all, do not use. If cooked it will emit an ammonia scent throw away and wash everything that it has come in contact with. In a hypo-chloride 5ppm solution minimum.
Filets can be frozen and most freeze well with the exception of cod which contrary to most does not freeze as good as we think it does.. This fish when frozen and then cooked cant hold its moisture content and therefore becomes a bit chewy and tough. Best way to freeze filets non commercially or home is dip in water and wrap in plastic, then take out dip in water again and freeze. This forms a protective ice coat on the fish that stops the dehydrating air from the freezer from affecting it..Some fish contain parasites which can be killed by freezing for 72 hours
Farm raised fish are usually not fed for the last 4 or 5 weeks before slaughter. Purpose being that with clean insides fish less subject to bacteria after slaughter. The fish are anesthetized in chilled water with carbon dioxide. They are killed by either being hit on the head or cut through the blood vessels of the gill and tail., because the blood contains enzymes and reactive hemoglobin iron, bleeding actually improves the flavor. Hope everyone found all of these facts interesting. In many cases frozen fish is actually fresher then so called fresh. It takes many days for fish to reach our shores from abroad, Then to the processor ,then wholesaler ,then retailer then us. Unless kept on ice and at same temps constantly quality suffers.
In many cases the floating fish factory processors is our best way to go. Within hours the fish are processed shipboard and flash frozen via nitrogen . The Japanese originated this form of aqua culture on board their factory ships. With the proviso that the fish is maintained in the same basic state (frozen) one can almost be assured of quality. Freezing today is a far cry from the antiquated ways of years ago. Chefedb60@hotmail.9/9/09 Chefedb60@hotmail.com