Freezing fish doesn't mean it will stay fresh, there are a few steps you will need to take to get the best quality out of your fish.
Remember when you freeze fish air is your enemy. Exposure to air causes the fish to dry out and freezer burn making the quality of the fish very poor.
A vacuum sealer is one of the best ways to freeze fish but these set ups can be costly and not economical for many people that don't keep fish very often. But if you keep a lot of fish a vaccum sealer is a great investment.
Another way to freeze fish without a vaccum sealer is to place the fish in a ziploc bag and fill the bag full of water with just enough room to seal the bag.
This will keep the fish in a block of ice where air cannot get to it. Using the vaccum sealer or the ziploc bag option you can expect to preserve your fish for 5-6 months.
After 6 months the quality will rapidly decrease so make sure to consume your catch before then.
When thawing never defrost fish in the microwave. The best way to thaw fish is by setting it in the sink and running warm water over it until thawed.