Do the thickness and color of the leash really affect the outcome?

Nylon or fluorocarbon are the primary materials used for leaders and shock leaders in sea fishing, and it’s no exaggeration to say that anglers generally agree that fluorocarbon is the most suitable. (Coated PE line is sometimes used as a leader, while polyester line is also used.)

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If you ask anyone with some fishing experience which one they would choose for a leader between nylon and fluorocarbon, regardless of the type of fishing, nine times out of ten they would choose fluorocarbon. The main reason is that it has a high specific gravity so it sinks easily in water, it is stronger underwater than nylon but has less elongation, has good sensitivity, is resistant to damage caused by brushing against underwater reefs or obstacles, and is less visible to fish so it does not cause them to be wary.

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However, in addition to choosing a line based on material, many anglers also have questions about the thickness (size) of the line and whether it is okay to use a colored line.

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To quote again the conclusions from the previous post,  “Do fish recognize colors?”, fish can be divided into species that can distinguish colors, species that cannot, and species that are colorblind.

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【Fish species that identify colors】

Sea bass, mullet, black rockfish, flounder, rock bream, flatfish, black sea bream, eel, etc.

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Fish species that cannot distinguish colors

Squid, mackerel, sharks, and other deep-sea fish where light cannot reach

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※Other octopuses, cuttlefish, and squid are color blind.

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The above distinction is the result of extensive research in the academic world. Now, with the red sea bream fishing season approaching, red sea bream is listed as a species that can distinguish colors. Let’s take a look at the results of an experiment to see if this is indeed the case.

The lines (fishing lines) used in the experiment are as follows.

· Fluorocarbon No. 14

· Fluorocarbon No. 1.2

· PE line 1.5 (composite)

· 1.7 translucent yellow nylon line

◉ When using No. 14 fluorocarbon as a leash

The red sea breams that spotted the bait and approached it turned away without taking it. However, they later took the bait.

◉ When using 1.2 fluorocarbon as a leash

The red sea bream that spotted the bait and approached immediately ate it. Clearly, the feeding behavior of the fish with a thinner leader is completely different from that of the fish with a thick No. 14 fluorocarbon.

◉ When using colored 1.5 PE line (composite yarn) as a leash

Upon spotting the bait, they immediately approached it, but then turned away from it. However, after a few explorations, they returned and were observed eating the bait.

◉ If you use 1.75 yellow colored nylon as a leash

They were seen approaching the bait, but turning away when it got close, and later returning to eat the food.

◉ Experimental results

We were able to find out that the thinner the leader, the less wary they were when eating the bait. The thin leader may have something to do with the sinking speed due to the weight of the leader and the appearance underwater, but the experimental results showed that when a thick and colored leader was used, the red sea bream that came up to the bait turned its body and moved away.

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We also found that red sea bream were more wary of colored PE lines and nylon compared to fluorocarbon.

However, in the end, we saw that the sea bream ate the bait on all the leaders, and this was an experiment that confirmed that when the target fish species is not very active, it is better to use a thin leader and, if possible, a transparent line without color.