River Peak introduces tenkara fluorescent yellow FC level line

Fluorescent yellow level line, that appears to be of an intense color, might be a good choice for visibility in some situations. For example, I find orange line difficult to see in early spring against a back ground of brown leaves. I’m pretty sure that last spring I orders a spool of the Sunline white nylon level line from Tenkarabum, but I also don’t recall fishing with it. It seems to have disappeared somewhere in the house.

This River Peak line might be an interesting alternative to the Yamatoyo fluorescent chartreuse fluorocarbon tenkara line. Just a bit more difficult to order.

50m ( 164ft ) spool,
sizes: 3.0号 ~ 4.0号


However, an alternative is the level line nylon ( レベルライン ナイロン) n-Vision tenkara wazashi level line in fluorescent vivid yellow (蛍光ビビッドイエロー). I think has been around longer, and is available in more size choices.

As required by nylon having a lower density, specific gravity. 4.6号 nylon is said to be equivalent in weight to 3.0号 FCLL. The tenkaratrain blog’s opinion on those lines from a couple of months back:


And an earlier post, first use of the nylon tenkara wazashi line.



Do you have any idea about test wt. in nylon as compared to Japanese fluro ratings? I saw some nylon line in several great colors and wasn’t sure if 10-12-15 pound was similar to 3.0, 3.5, or 4.0. It may have been discussed before but I can’t find anything. I’m just wondering if this is a good alternative. Any thoughts would be appreciated.
Please, if anyone else knows or has experience, please chime in. Thanks

The old yoz-ami (YGK) website used to have several pages in English that was pretty through explaining world wide line rating methods. The best I ever found on the internet. The Japanese measure line, or rate line differently than it is done in Europe, which is different from the way it is done in America. The European system was kind of half way between the American and Japanese method. But unfortunately I can no longer point you to the yoz-ami pages as they took it down a few years ago.

The general thumb rule is x4.
2号×4=8lbs ; 5号×4=20lbs.

But it really depends on which lb. rating you are seeing on the spool of line. lbT or lbC:

American made line generally uses lb.-test (lbT) which means the line is guaranteed not to break below that rating. iow, 8 lbT line will not break below 8 lb. It also might not break at 12 lb. and finally break at 15 lb.

The other lb rating is lb. Class (lbC) which is kind of the opposite of lbT.
8 lbC line is guaranteed to break at or below 8 lb. It might break at 6 lb. or 7 lb. But will definitely break at 8.1 lb.

Maybe the following website will help. Even with the odd translations. It has some explanations, plus tables for FC, Nylon and PE lines.


Google translation of https://ms-fishing-style.com/ozgglb/linestandard

btw & fwiw - years ago I did some research into the Japanese line 号 or 号数 rating system, trying to understand it. It appears that the only standard set by Toray ( I think in the 1960s or earlier) is for nylon line of 1 号 = .165mm diameter. Which was itself based on an ancient method of measuring silk thread. All other lines; FC, PE and lines of larger or smaller size are just kind of on the honor system to have other size lines be in compliance with their line size tables & that nylon reference size.

The line sizes are not ratios of the line diameter. They are ratios of either line cross section area or ratios of the line weigh.

[ it is difficult to measure small line diameters so lines are measured by denier weigh ( X grams/9000 m) during manufacture. If 9,000 m of line has the correct gram weight for say 3号line, then the average diameter of the line will be correct at 0.285 mm +/- manufacturing tolerance.

Or another way to understand the Japanese line system is 4 号 line will have 4x the cross section area of 1 号. (It’s easy math. pi * r^2. for 0.330 mm vs 0.165 mm line → 4 号/1 号 = 0.08553/0.021382 = 4.000094) I can never type that formula with seeing either Jethro or Granny Clampett saying, “No, pie are round - cornbread are square.” :roll_eyes:

Anyway, 4 x X 号 seems to be common thumb rule.
But I think new chemical mixes for making the lines. Throws lines off the standard lb rating vs standard line diameter table.


Maybe this half-way answered your question. :open_mouth:

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Thank you very much for the information.

I would rather someone produce a strong white level line. I use the Sunline Vision line that TenkaraBum sells, but it doesn’t perform quite as nicely for me as Nisshin PALS Oni level line.

I wonder if either if this fluorocarbon line is more white than clear color?

The title says - transparent white color. However, it’s also listed as clear. But in the pictures it looks white against a black background.

I also wonder what the difference is between made in Japan & material from Japan. Sounds like a phrase dreamed up by lawyers & marketing salesmen, not technicians on the factory floor.


Interestingly in their table showing X 号 , line diameter, lb. The conversion on average is X 号 x 4.5 + / - . A little different from the x4 thumb-rule. But chemical formulas for making fluorocarbon keep getting stronger.

I also found Seaguar Invizx FC line that looked more white than clear transparent, but in reviews there were many comments about it having a lot of coil memory that caused problems coming off their reels. And I think no one likes tenkara fishing with a long slinky.

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@dwalker A long slinky? That might be good for fixed line tactical nymphing! You don’t happen to have a spare 20 feet of it lying around, do you?

That line is clear. Materials from Japan means the chemicals came from Japan and it was manufactured elsewhere, almost invariably China. Buyer beware applies here.
The invizx is not the latest version of Kureha’s lines, so some memory might be expected, but calling it a slinky is unwarranted. It also is clear. To the best of my knowledge nobody makes a opaque white fluoro, what would be the point? There are some interesting niche lines made for other uses, like squid fishing fluoro in sizes below 1.75, but they all seem to be orange for night fishing.

No sorry. I do not have any of the two previous mentioned lines. No Top Carbon FC line, nor the Seaguar Invizx. I do have, I think, some of the FC LL that TUSA sold ten years ago. It seemed to have a lot more coil memory that later FC LL that became available later.

If I recall correctly it was kind of pale green color. But maybe with more experience I just became better at stretching the line to remove most of the memory. I do not know what lengths I have, but if I can find it, I will sent it to you if you would like to have it. Just send me a PM with your address.

You can find many DIY videos on line how to make your own coiled slinky strike indicator, maybe a brighter color is better. Here is a how-to video Jason Klass uploaded about 10 years ago. But there are many others to be found - depending on the search phrase you use to find them.

How to Make the French Slinky Strike Indicator

One method of making one with much smaller coils.


The point seems to be that some people find a white line visible under certain conditions or otherwise desirable, but prefer the way fluorocarbon line cast.

They don’t want the white furled Fujino line, or white braided line, and do not like the way the white Sunline Visible Free nylon line cast, and would like to find a white fluorocarbon line. But maybe you are correct and no one makes one. I think you cannot tell how white a line is looking at it online, and would need to either see it in person or order it and take a chance it might prove suitable. I haven’t tried fishing with a white line so have no idea whether I would like it or not. But you never know unless you’re willing to experiment with it.

Two colors, wrapped on a nail for 30 small coils. Jump to 1:30 minutes in the video.

https://vimeo.com/RIO’s Two Tone Indicator Tippet - plus how to make the “Slinky” Indicator

The same concept of hot water was used in the early years of fluoro use by saltwater guys to remove the coiling. We’d fill a bathtub with 6” of the hottest water we could make, throw the 100# test fluoro in, pull it out 5 minutes later, gently stretch it out straight for 5 minutes, bingo.
Fluoro has gotten sooooo much better since then!