Freezer-burn ruins a lot of meat, fish, and vegetables every year.
It is caused by air leakage in the packaging, which allows the moisture to escape, drying out the contents. The drying out process leaves the product looking as if it was burned and it is ruined as far as human consumption is concerned.
This situation can be totally prevented by proper packaging and gentle handling of frozen items.
The most thorough and protective method of wrapping is to use two layers. Place the product in a light plastic baggie such as a produce bag available on rolls at grocery stores. One of these rolls will last a number of years before you need to buy again.
A heavier-duty plastic bag will seal the product adequately, but sadly when plastic bags are frozen they become brittle and easily broken by rough handling in the freezer. The resulting break in the plastic bag allows an air leak, leading to freezer burn.
Squeeze the air out of the bag manually and then spin the bag to twist and seal the top. Then wrap the plastic bagged item in butcher paper also available at grocery or outdoor stores.
This paper has a plastic or vinyl coating on one side that should be wrapped on the inside. A little experimentation will have you cutting the paper the right size to avoid wastage.
Turn the square of paper so it is a diamond. Set the product down close to the bottom point of the diamond and roll the paper up over the product about halfway, then fold the sides in to seal them. Continue rolling to maintain the seal at the sides up to the top point of the diamond.
Freezer tape is available but masking tape works very well and is much cheaper. The tape should go completely around the package so the end of the tape is fastened to the beginning of the tape.
The tape should wide enough for you to label the package with a felt marker. Your label should name the package contents and the date.
This double seal technique prevents too much leakage from thawing meat.
It takes a little more time and expense to double wrap, but this way fish will keep for at least twice as long and meat will keep for at least two years.