I almost never freeze meat or fish. But if I do, I use a vacume sealer and only keep the food frozen for a week or less. I do keep a 2 lb bag of frozen shrimp in the freezer for a month or more. But those are flash frozen using a glazing method to cover them individually in ice. And besides, they're convenient as he## for throwing together a quick, inexpensive and tasty meal.
I found these guidelines
here.....
"How long can you freeze your fish? Never longer than 6 months. After that, you will notice a serious decline in quality. Fatty fish, such as salmon or trout, go down hill even faster: Don't freeze them longer than 3 months.
And some fish should never be frozen. These are the fattiest ones, the bluefish, herring, mackerel and sardines. You can glaze them, but they still decline in quality a lot. If you find youself with a surfeit of bluefish -- this happens a lot -- vacuum-seal them and know that you will be making fish cakes with them down the road; that's all they'll be good for.
When you thaw your frozen fish, do it gradually. Never put them in the microwave to thaw!! Let them thaw in the fridge or in cold water. Thawing at room temperature is also a bad idea."