Fishing line is the direct connection between you and a fish, and the choice of line matters more than most anglers give it credit for. The wrong line for the application does not just cost fish – it costs fish in ways that are hard to diagnose because the failure is invisible until the line breaks.
This guide explains the three main line types used in UK coarse and sea fishing (monofilament, fluorocarbon, and braid), what each is for, how to choose between them, and the practical decisions around breaking strain and diameter.
[Image placeholder: Three spools of fishing line side by side – a clear monofilament, a near-invisible fluorocarbon, and a dark green braid, showing the visual difference between the three types]
Monofilament (Mono)
What it is
Monofilament is a single continuous strand of extruded nylon. It is the most widely used fishing line in UK coarse fishing and the default choice for most applications.
Properties
Stretch: Mono stretches – typically 15-30% before breaking. This stretch is both an advantage and a limitation.
Advantage: Stretch acts as a shock absorber when a fish runs, when you strike, or when a fish lunges near the net. On light tackle with small hooks (size 18-22), the stretch in mono is what prevents the hook pulling free or the line snapping on a sudden run.
Limitation: Stretch reduces sensitivity at range. When fishing a feeder at 60+ yards, the 20% stretch in 30 yards of line means you are pulling through several inches of stretch before the hook sets. At very long range, mono’s stretch can cost fish.
Buoyancy: Mono is approximately neutral in density, with some lines designed to float (surface float fishing) and others slightly sinking. A floating mainline helps keep a waggler trotting naturally in current.
Diameter: Mono diameter is larger for a given breaking strain than braid (though smaller than it used to be with modern formulations). Modern fine-diameter mono (e.g., 0.14mm at 3lb) is considerably thinner than previous generation products.
UV degradation: Mono degrades with UV exposure. Replace mainline annually if regularly used; check and replace hooklinks more frequently.
Knot strength: Mono knots well. The grinner (uni knot), blood knot, and palomar all perform reliably in mono.
When to use mono
- Float fishing: The default choice for waggler, stick float, and river float work. Choose a floating mono for wagglers to keep the line above the surface between float and rod tip.
- Feeder fishing at moderate range: Up to 50 yards, mono handles feeder work well. The stretch is not a problem at this range.
- Hooklinks (hooklenghts): Mono hooklinks are fine for most coarse applications – roach, bream, tench, chub. Use lighter mono than the mainline: 1-2lb hooklink to 3lb mainline, or 4lb hooklink to 8lb mainline.
- General carp fishing: Many carp anglers use 10-12lb mono mainline on a standard carp rod. It is forgiving, buoyant (helps the lead presentation), and cheap to replace.
Typical breaking strains in UK coarse fishing
| Application | Breaking Strain |
|---|---|
| Pole elastic hooklink (fine) | 0.5-1lb |
| Waggler for small fish (bleak, roach) | 1.5-2lb |
| River float or canal roach/bream | 2-4lb |
| Feeder, tench, general coarse | 4-8lb |
| Carp, barbel mainline | 8-15lb |
Fluorocarbon
What it is
Fluorocarbon is a line made from polyvinylidene fluoride (PVDF). It looks similar to mono but behaves differently in water.
Properties
Refractive index: Fluorocarbon has a refractive index (1.42) very close to water (1.33). This means it bends light at nearly the same angle as water, making it significantly less visible in the water than mono (refractive index 1.5) or braid (higher). It does not become invisible, but it is considerably less conspicuous.
Density: Fluorocarbon sinks faster and more completely than mono. It hugs the lakebed on a hooklink, which is often desirable for ledger and bolt rig presentations where you want the hooklink lying flat on the bottom.
Low stretch: Fluorocarbon has less stretch than mono. This improves sensitivity and hook-setting at range.
Durability: Fluorocarbon does not degrade with UV exposure and is highly abrasion-resistant. Useful on gravelly, rocky, or snaggy bottoms. Hooklinks in fluorocarbon last considerably longer than mono hooklinks in the same conditions.
Stiffness: Fluorocarbon is stiffer than mono of the same diameter. This can cause kinking on spools if not managed properly. It is not suitable for light float presentations where a supple hooklink is needed.
Cost: More expensive than mono, which is why it is typically used for hooklinks rather than mainline.
When to use fluorocarbon
- Hooklinks on clear water lakes: On pressured gravel pits or clear estate lakes where fish are finicky, a fluorocarbon hooklink instead of mono can make a measurable difference. This is where fluorocarbon earns its cost.
- Bolt rig hooklinks: Fluorocarbon lies flat on the lake bed, which helps the hook bait sit naturally and prevents the hooklink from being detected by cautious fish.
- Chub and barbel hooklinks in clear rivers: In low, clear summer conditions on chalk streams and clear rivers, a fluorocarbon hooklink reduces visibility without sacrificing strength.
- Mainline for lure fishing: Fluorocarbon mainline or long fluorocarbon leaders are used in clear water lure fishing for perch and zander where braid visibility would reduce takes.
Braid
What it is
Braided fishing line is made from multiple strands of ultra-high-molecular-weight polyethylene (UHMWPE) – typically Dyneema or Spectra – woven together. It is a fundamentally different product from mono or fluorocarbon.
Properties
Zero stretch: Braid has effectively no stretch. At any distance, a bite is transmitted instantly. This makes braid dramatically more sensitive than mono at range.
Small diameter for breaking strain: Braid is typically one third to one quarter of the diameter of mono at the same breaking strain. 30lb braid is typically 0.28mm diameter. The equivalent mono would be nearly 0.6mm. The thin diameter means less water resistance on a spool (better casting) and allows smaller reel spools to hold more line.
No UV degradation: Braid does not degrade with UV exposure and is highly abrasion-resistant.
Visibility: Braid is visible in the water. This is typically managed by using a long fluorocarbon leader or hooklink. For carp fishing at range, a 12-15ft fluorocarbon leader is normal practice.
Knot considerations: Braid requires different knots from mono. A standard blood knot slips in braid. Use a Palomar, a braid-specific Grinner with extra turns, or a PR knot for heavy braid connections. Braid-to-leader connections typically use an FG knot (lure fishing) or a half-blood knot through a swivel.
Line feel: Braid transmits vibration from the bottom as the angler retrieves or tightens the line. Experienced feederers and carp anglers use this information to read the lake bed (gravel feels rough through braid; weed feels soft).
Cannot use on all reels: Very light braid (under 10lb) can cut into packed spools on a standard fixed-spool reel. Many anglers use a mono backing with a braid topshot to prevent this.
When to use braid
- Long-range feeder fishing: At 80-100+ yards, braid’s lack of stretch dramatically improves bite detection and hook-setting. A 12-15ft fluorocarbon hooklink prevents the braid leader from being detected. This is the standard approach for long-range bream and barbel on rivers.
- Lure fishing: Braid is the preferred mainline for most lure fishing. It transmits lure vibration directly, allows instant hook sets, and the small diameter means less casting resistance. Use a 15-30ft fluorocarbon leader to the lure.
- Spod and marker rods: A dedicated spod rod runs braid mainline (typically 30-50lb) for its small diameter and zero stretch, giving accurate spod placement and a tight line feel when marking depths.
- Sea fishing lure fishing: Bass and pollock lure anglers use braid almost universally for the same reasons – sensitivity, small diameter, and distance.
When not to use braid
- Light float fishing: Braid sinks and drags floats down. Do not use braid as float fishing mainline.
- Hooklinks on carp rigs: Never use raw braid as a hair rig hooklink without a fluorocarbon or coated braid conversion – it is too visible and behaves incorrectly on the bottom.
- Where rules prohibit it: Some fisheries ban braid mainline. Check venue rules.
Coated Braid Hooklinks
A significant category in carp and tench fishing. Coated braid hooklinks consist of a braid core (strong, flexible) covered in a polymer coating (stiff, sinking). The coating is stripped back 2-4cm near the hook end, leaving a supple braid “kicker” that allows the hook to turn freely.
Benefits: The coated section lies flat on the lakebed (like fluorocarbon). The stripped section allows natural hook movement. The braid core gives high strength in a small diameter. Most serious carp anglers use coated braid hooklinks at 15-25lb in 6-12 inch lengths.
Practical Decision Guide
| Fishing | Mainline | Hooklink |
|---|---|---|
| River float (roach, dace, chub) | 3-4lb mono (floating) | 1.5-2lb mono |
| Canal match | 2-3lb mono | 0.75-1lb mono |
| Still water waggler | 3-4lb mono | 2-3lb mono |
| Feeder (close-medium range) | 6-8lb mono | 4-6lb mono or fluorocarbon |
| Feeder (long range) | 15-20lb braid + leader | 6-10lb fluorocarbon |
| Carp (standard) | 10-12lb mono | Coated braid or 15-20lb fluorocarbon |
| Lure fishing (perch, pike) | 15-20lb braid | 15-20lb fluorocarbon leader |
| Barbel (river) | 8-12lb mono | 6-8lb fluorocarbon |
Frequently Asked Questions
Does higher breaking strain always mean thicker line?
In general, yes – within the same line type and manufacturer. However, modern high-specification mono can offer 8lb in a diameter previously reserved for 4lb products. Always check the actual diameter (in mm) rather than relying on breaking strain alone when comparing lines.
How often should I replace fishing line?
Mainline mono: replace annually if used regularly, or sooner if you notice kinking, fading, or any rough sections. Fluorocarbon hooklinks: replace if visibly damaged or after a fish has been caught and fought hard – check for nicks from teeth or gravel. Braid mainline: more durable, but check the first 5-10 metres regularly for wear.
Can I use braid as a hooklink for carp?
Raw, uncoated braid as a hooklink is not recommended – it is too visible in clear water and does not behave correctly on the lake bed. Use coated braid, stripped at the hook end, or fluorocarbon hooklinks. Braided hooklinks are used in specific weedy situations where a highly supple, high-strength link is needed to prevent weed wrapping.
What does diameter in mm mean on a spool?
The diameter (mm) is the width of the line strand itself. It determines how much line fits on a reel spool and how visible the line is in water. 0.20mm is a typical 4-6lb mono. 0.25mm is a typical 8-10lb mono. Braid is much thinner: 0.10mm braid may be rated at 10-12lb.
Is expensive line worth it?
For mainline, mid-range products from reputable manufacturers are fine. The biggest gains from premium line come in hooklinks on pressured waters – where low-visibility fluorocarbon or ultra-supple coated braid makes a measurable difference to bite rate. Cheap hooklink materials are a false economy.