how long to freeze for?

[lesleyanndunn]

i've just bought some mussels in black shells
and one oyster in a shell
to try with abe (fahaka)
as a change in his diet
i bought them fresh today
and have put them in the freezer.

how long do you have to freeze to kill off the nasties?
before you can defrost one and feed?

[jus85411]

whenever i got them i just wait 24 hours to feed them. i dont know if there is a set timeframe. if they are live then they might take a little while because usually coldness will make them lay dormant for a while. once i froze them for a few hours and thought the clams would be frozen and good to feed but they were still alive and stuck shut still. with the clams i got they will be closed when they are freezing and open a little when defrosted

[HGI]

I know when I worked at a sushi bar any sea food that was going to be served raw had to be frozen all the way threw in order to kill parasites before it was thawed and served (except for ahi tuna that was served fresh). So I'm going to say a 24 freeze would be safe enough.

[lilacamy931]

I was really over precautious and froze for a week to make sure no nasties and they were dead.

[Nick]

This is actually a more complex question than it sounds like, because the effect of freezing materials made of cells changes radically depending on how quickly the freezing progresses and how consistent(and low) the final holding temperature.

A slow freeze makes large water crystals. Large water crystals damage cellular organelles, membranes, and even cell walls - this is why frozen veggies thaw to much softer than fresh, while meat thaws with much less trouble, because it is muscle and thus composed of many layers of contactable fibers woven together with nuclei embedded periodically to take care of things; having no specific cells, it thaws to something quite resembling the original product.

Flash freezing makes TINY water crystals. It does some damage to certain cells and organelles, but many cells can actually be thawed and survive, individually, from a VERY fast freeze. Likewise, certain animals work around slow-freeze tissue damage. Lets say wood toads as a specific example, as they are the most iconic - buggers freeze totally for two weeks to 4 months of the year.

When their body drops to near freezing, they break down an energy storage starch(yes, 99% of the time animals store energy as fat for hibernation as fat is much denser calories than is starch, however, these toads need a very quick way to fill their organs and cellular tissue plasmas with glucose, other sugars, and glycerol - which work like antifreeze, keeping the water in organs and other bodily cellular structures unfrozen, while allowing normal freezing in the areas between organs and other places where it's irrelevant if large bits of ice form - including the eyes, which cloud with freezing but fix up perfect in the spring.

Ultimately 60% of the frog is frozen solid, and the remaining 40% is carefully freeze-protected but essentially biologically intern for the duration of time spent just below freezing. These frogs do not burn stores of fat and protein to stay alive with a highly reduced metabolism like most hibernating creatures, they actually enter a stasis which has essentially zero energy cost DURING THE STASIS ITSELF.

So the frozen frog is basically a meaty ice cube, however, just as a bear must fatten up to survive its hibernation, the production of sugars and glycerol to protect key body systems from freezing requires some advance energy storage on the part of the frog. In this case a carbohydrate is used, as turning a properly structured carbohydrate into sugars and glycerol is biologically easy (perfect for a frog with bio-functions quickly getting near nonexistent), while making them from fats is much messier though possible.

A highish(between 32 and 0 degrees F for the most part) holding temperature will experience some recrystallization and other processes which eventually (over months or years) degrade the frozen product.

Fluctuating temperatures from right around freezing to the deep freeze range will result in larger crystals gradually forming in erratic locations as well as "freezer burn" a condition created where the combination of conditions (usually due to a freezer being opened regularly) create an environment so devoid of moisture that ice crystals evapo-transpirate to water vapor, entirely bypassing the liquid phase. When this damages frozen foods, it's quite obvious, nearly everyone has had some contact with a freezer burned meal.

So, I was talking about freezing to protect consumers of fish products, be they myself or my puffers, from getting diseases or toxins. A SLOW freeze compromises the texture of the food more (moving it towards soft/slushy - which can actually be a GOOD thing when cooking something typically rubbery or tough) however it kills parasites, parasite eggs, and even monocellurlaro or smaller beasties like free-swimming ich/velvet quite readily. Even very tough parasite eggs are likely to die of either a slow freeze, or a week in the 32F to 0F window provided occasional check to the freezer.

A fast freeze kills certain things just as well as a slow freeze, but a totally unknown variety of whatsits can survive flash freezing because the ice crystals formed are not large enough to promise they are all dead. Deep freeze, with its ability to preserve the textures of frozen foods when that is important, is not for your health - slow freeze is more destructive to pathogens. I suspect quite a variety of bacteria and protozoans have ways of dealing with freezing temperatures IF the freeze itself or the holding conditions are right.

TL:DR(too long, didn't read)
Ice forms when things composed mostly of water are freezing and all kinds of chemicals are not preventing it. Ice which freezes slowly forms into bigger crystals which breach the containment of nearly any tissue you freeze, be it an egg, a turnip, or what have you. Bad holding conditions with changes in temperature due to household factors like too many people "checking the freezer" or "grabbing abeer"