Easy Reel-In:
Once the fish bites and starts swimming quickly to the left, tap "X" once. When the fish slows down, reel it in. It should not struggle. (This does not work on the "Lake" level.)

Catch fish faster
Press [X] once a fish is hooked and starts to swim quickly to the right. Wait for it to slow down, then reel it in. The fish should not struggle. Note: This technique does not work very well on the lake level, or if the fish arches back to try and pull free.

Note: This trick works well in the stream/creek level. Watch for bubbles to appear just before the fish takes the bait. Press [Circle] + [X] when the bubbles appear to quickly reel in the line without fear of breaks.

To catch a fish faster, once you hook it, quickly press [Circle]. It will be reeled in for you.

Heavy fish
Get a fish on the hook. Then, hold [Down] + [X] when the fish slows down. If it tries to break free, let it go -- just repeat the step after it slows down again. This should result in a close-up of the fish while reeling it in. Once you catch the fish, land it by holding [X]. The fish should be huge and very heavy. Note: This can also be used with catch fish faster trick.