You have to watch the lure carefully. Sometimes the fish pulls it completely underwater on the first try, other times it takes more than one try. Once the lure goes completely under water, activate the spell (I have to press the space bar on my system to do that). If you still cannot catch something, buy an elixir to boost your luck (crown shop) Good luck!
First, make sure that you're waiting until the lure drops completely below the water. As soon as it goes down and stays down, that's when you hit the space bar. If you're doing that and the fish are still swimming away, that is a sign that you're using too weak of a lure, the wrong lure, or you just need to add some luck.
The luck boost potion is a crown shop purchase that can definitely help, but not everyone wants to spend real money. There are other things you can do in-game to improve your results.
The most basic tactic is to use the Reveal School Spell and select the correct school lure for the fish you're trying to catch. If you're after an Ice fish, then use the Ice lure and only go after fish with a blue light above them. It takes a lot of energy, but at least you know you're using the right lure for the right fish. You can get the Reveal School spell as soon as you hit rank 2 in fishing experience.
When you reach fishing rank 3, you should go to Timor Flamecaster inside the Labyrinth of Dragonspyre. He sells Winnow Fish (send away all but one type of fish) for each school. This is the way that you can make sure your lure will work on all the fish in a fishing hole.
Once you get to Grizzleheim and are a level 5 fishing rank, you can buy level 2 lures. Now things get even easier! For example, sending away all but the Fire fish, then using your rank 2 Fire school lure will help you catch a rank 2 Fire fish like Bear Acuda.
When you get to level 6 in fishing experience, there are other spells that will help you: Summon Fish (resets the fishing hole); Lure Fish (brings them all closer to you); and Sleep Fish (makes them all stop moving for a while).
Alia Misthaven