My advice when dealing with fresh fish products, buy fresh, freeze for 48 hrs at 0F (-18C) to destroy any potential parasites, and use up within 30 days or so. Freezing will not destroy all micro-organisms, so there is still some risk involved in feeding frozen products, but freezing certainly minimizes those risks.
Freezing tends to also increase the concentration of thiaminase in tissue, so the shorter the duration in the freezer, the better. Little is known as to how thiaminase affects various species, and according to various studies the amounts found (even within the same species of fish) tend to vary as well.
Most public aquariums tend to supplement to avoid deficiencies. (especially B1 & vitamin E)
With regards to thawing, while thawing under running water is not ideal, the result of doing so will certainly not eliminate all nutritional value of the food. I would also concur with Zinq, the bacterial growth that would take place from thawing under warm water would be negligible. Nevertheless, certainly not an ideal way of thawing frozen food.
The USDA as well as most state health departments have outlined what they feel is the "best" way to unthaw fresh fish products. You can find those methods in the link below.
http://www.aphis.usda.gov/animal_welfare/downloads/marine_mammals/mmfish.pdf
This may be one of the documents that Zoodiver was referring to, definitely a good read for those not familiar with it.
Also note that even frozen fish that have been unthawed under refrigeration , should be fed within 24 hrs. (or discarded)
Another good read on this subject can be found in the following link.
http://www.nagonline.net/Technical%20Papers/NAGFS00597Fish-JONIFEB24,2002MODIFIED.pdf
HTH
Freezing tends to also increase the concentration of thiaminase in tissue, so the shorter the duration in the freezer, the better. Little is known as to how thiaminase affects various species, and according to various studies the amounts found (even within the same species of fish) tend to vary as well.
Most public aquariums tend to supplement to avoid deficiencies. (especially B1 & vitamin E)
With regards to thawing, while thawing under running water is not ideal, the result of doing so will certainly not eliminate all nutritional value of the food. I would also concur with Zinq, the bacterial growth that would take place from thawing under warm water would be negligible. Nevertheless, certainly not an ideal way of thawing frozen food.
The USDA as well as most state health departments have outlined what they feel is the "best" way to unthaw fresh fish products. You can find those methods in the link below.
http://www.aphis.usda.gov/animal_welfare/downloads/marine_mammals/mmfish.pdf
This may be one of the documents that Zoodiver was referring to, definitely a good read for those not familiar with it.
Also note that even frozen fish that have been unthawed under refrigeration , should be fed within 24 hrs. (or discarded)
Another good read on this subject can be found in the following link.
http://www.nagonline.net/Technical%20Papers/NAGFS00597Fish-JONIFEB24,2002MODIFIED.pdf
HTH
