Choose line by diameter, material and the weakest connection

Start with the whole setup

Identify the method, expected fish, water type, likely snags and the rod and reel being used. Then read any venue rules on main-line material, minimum diameter, leaders or braid. A line that is suitable on an open stillwater may be inappropriate around rocks, weed or powerful river flow.

Do not choose an artificially light line for presentation alone. Landing fish efficiently and avoiding breakages are part of fish welfare.

Understand the main materials

Nylon monofilament

A common main-line choice with some stretch and broad knot compatibility. Diameter, suppleness, abrasion resistance and memory vary between lines.

Fluorocarbon

Usually denser and less visible in some conditions, but often stiffer and different at knots. It is not automatically the best main line or hooklength for every method.

Braid

Very low stretch and high strength for its diameter. That directness can improve indication but reduces cushioning and may be restricted by a fishery. It needs compatible knots, guides and careful fish-playing technique.

Read the spool beyond breaking strain

• Use diameter when comparing capacity and physical thickness.
• Check whether the stated strength and diameter apply to the same product version.
• Follow maker guidance for knots and wetting or tightening them.
• Match hooklength and main line so the intended failure point is understood.
• Use shock leaders only when the method requires one and the venue permits them.

Inspect, replace and dispose

Before fishing, run the final section carefully between your fingers away from the hook. Retie after abrasion, a snag, a damaged knot or unexplained weakness. Replace line that has become rough, flattened, brittle or badly coiled.

Collect every trimmed piece immediately. Store waste line and hooks in a closed container, cut long discarded line into short sections at home where the chosen recycling or disposal scheme instructs, and never leave it on the bank.

Use the capacity estimator, then practise the connections in the beginner knot guide.