Choosing the right fly rod
The right rod matters. You simply have to think of the fly rod as a tool. Just like choosing the proper screwdriver for a particular job. A fly rod has different “weights” 1 to 10 with 10 being more stiff than 1 and length of rod. You simply choose weight and length of the rod based on 3 components:
How hard do you have to set the hook to penetrate the type of fish you are trying to catch. Bass have harder mouths than trout.
How far do you need to cast your line. The length of the rod affects the distance you can cast. Longer rods potentially cast farther than shorter rods. Most rods are 8 to 9 feet long. Longer rods for bigger water but 9 foot 5 weight will pretty much handle most of your trout conditions in the USA.
How much control over the fish do you need when fighting them. The higher the rod weight the more control you have. You want to enjoy the fight but not manhandle them like you would if you had a broomstick as a fly rod. A too light of rod and you will be like using a wet noodle trying to fight the fish.
Common rod ranges for particular fish are as follows:
Weights — Bluegill 2 to 5 / Trout 2 to 6 / Largemouth bass 8 to 10 / Saltwater 8 to 10 or higher
Your local fly shop will have a good variety to choose from plus they will often allow you to practice casting the rod before you buy. This is a very nice service because not all rods are the same. Each brand has their own way of making them which affects how they cast.