Overview
Produced in Japan with strict quality control, the Shimano Mastiff FC Fluorocarbon Line offers all the characteristics you want in a premium 100% fluorocarbon to enhance performance on the water. Devised NANOARMOR technology, Mastiff FC Fluorocarbon Line features nano-size ridges across the outer surface of the line to enhance knot strength, toughness, prevent slippage, and reduce the risk of the line breaking. The added knot strength and durability are essential for enduring the repetitive stress when casting, jerking large lures, and dragging along structure.
Not only is Mastiff FC Fluorocarbon Line incredibly tough, but it also provides incredible smoothness for enhanced casting and is reliably consistent to increase your performance on the water. No matter if your finesse fishing with small worms or flipping heavy cover, the Shimano Mastiff FC Fluorocarbon Line delivers connected confidence on the water.
| Line Size | Diameter (mm) |
| 4lb | 0.17mm |
| 5lb | 0.19mm |
| 6lb | 0.21mm |
| 8lb | 0.24mm |
| 10lb | 0.26mm |
| 12lb | 0.29mm |
| 14lb | 0.31mm |
| 16lb | 0.33mm |
| 18lb | 0.35mm |
| 20lb | 0.37mm |
Awards
ICAST 2023 Best of Show - Fishing Line
Pro Using This Product
Videos
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Customer Reviews
8lb test used snapped on 4lb bassI was dropsotting this line as a leader line and my biggest fish of the tournament broke the like at the hook. This could have been a user error except same day it broke again on a fresh leader. Probably why they are giving this stuff away.
Don't use for ultralight applicationGreat line, but as other reviewers mentioned, its super stiff line with high memory. I put the 4# on my ultra light bc I got the line for 5 bucks with a shimano purchase. You will have coiled line after the first few outings. Have not tried the line in other applications, but it seems to be a good strong line for the right scenarios.
Excellent for leaders/TopshotsLearn how to set the drag. Too many people complaining about break offs. 99% of the time that is human error.
Mastiff is very stiff (Duh, its in the name) and that means it has VERY LITTLE stretch HIGH abrasion resistance HIGH memory and EXCELLENT sensitivity.
You can use it for a mainline, but you need to set the drag properly because of the low stretch, and the memory is severe. It has the worst memory of any line i have fished, thanks to the density and stiffness of the line. I didnt enjoy using it that way. Braindead anglers who think they are setting the hook on a tuna and horse fish to the boat seem to have problems with mastiff because they use too much drag.
Using it as a leader line on braid however? The absolute bomb. Low stretch and high sensitivity are a kickass combo, ASSUMING YOU KNOW HOW TO SET THE DRAG.
Mastiff is great line, but you need to know how it works in order to use it properly. The lack of stretch really seems to be a dealbreaker for many. The memory really holds me back from using it as a mainline despite how much I want to do that. The low stretch and sensitivity is incredible, but that came at the cost of memory.
Easy break offTried 12lb flouro. It broke easily. Don’t waste your time buying this one. Not even as strong as 12lb seaguar or Vanish.
Not a fanProduct seems to coil quicker than my seaguar.
Top notch fluorocarbon line.Shimano hit it out of the park with this one. Very abrasion resistant, smooth, low memory , strong, ties a good knot. No troubles from the 20lb test. Just wish it came in bulk spools.
Breakage IssuesTried 10lb for leader and broke off 4 times. I thought may have been a bad spool but other friends have mentioned same issues.
Impressed with this line!My review is for the 14lb and 10lb line. I use straight 14 for chatterbaits and northern swimjiggin. 10lb I use for leader on spinning setups.
Knot strength: I feel it is as advertised, very good on connector knots and direct to bait. Need to lubricate first.
Line strength: I have used for 6 months with no break offs of connector knot breaking even when snagged. 10lb diameter is thinner than some 8lb brands and I feel more confident I wont break off upping my lb test.
I am a fan of sufix advanced floro and I would say this is as strong but with smaller diameter.
Would recommendI got the 18lb for river smallies. I used it for squarebills and chatterbaits and soft jerkbait s with no issues. It is stiffer and has memory but after a few cast it's good to go again haven't got any backlashs or snap offs if I get snagged on a rock or log I 9 times out of 10 get my bait back because it'll bend the hooks before it breaks I'm buying more now
No positives14lb line was nothing but trouble. It did not cast well at all and was stiff and coiled up. To make matters worse I lost two baits just from simply casting so I have to assume the knot strength isn't good. I can't tell you the last time I lost a bait just from casting but with this line I did it twice in an hour.
Mastif for leadersJust came back from a Canada trip and the 8# and 10# Mastif leaders I tied with my braided lines worked great! Easy to tie. Using 10# X9 braid and a Crazy Alberto knot, all knots were strong and did not fail on any of my glass spinning crankbait rods. They even held up to numerous pike that seem to hammer my crankbaits. Highly recommended. I plan on using 20# Mastiff on my heavy swimbait baitcasting rod.
Love it......But!Great line and so far i love it but thwy need a bulk spool not a fan of having to buy 3 or 4 spools of the same size
Ok line, wouldn't buy againI got a spool of the 18lb for free as a product tester. And it's decent line. Like I never broke off or anything like that. It is strong and has good abrasion resistance. It just seemed to dry out faster and get more coily faster than my other fluorocarbons I use. I spooled all of my rods at the same time so it was just weird. It's not super expensive which is probably why. The thing that bugs me the most about this stuff is that they don't have bulk spools. Which is another reason I won't buy. I go through way too much line to buy 200yds at a time. That's so much more expensive than bulk spools. I might try this stuff as leader line because I think it would excel at that. But for mainline I am not the biggest fan.
Awesome line - very fair priceHave used the 20lbs all the way down to the 5lb and it seems like very high quality line for a really reasonable price. Spooled evenly on the spool that it comes on - not too much stretch, but great abrasion resistance.
Use it for leader material as well as main line. And the main benefit is the knot strength so far so good after one full season!
The Real DealI'm using 20lb for skipping jigs around docks. Line is performing exceptionally well with abrasion resistance and memory. Knot strength is great and I'm still having a hard time wrapping my head around the small diameter. The 20lb test feels like 15lb. GREAT PRODUCT!
My New Favorite LineI bought the 20 lb spool for fishing big glidebaits and big soft baits. I love it. I have not snapped off any baits casting or setting the hook like I would with my previous line. The aberration resistance is incredible. And I love the smaller line size with the amazing strength still there. Also, knots tie amazingly. But we do need a bulk spool. Overall great line.
Very thin in sizeI really enjoying this line, getting more poundage with thinner line size! I was flipping with the 16lb and hooked into a 8 1/2 large mouth and I just horsed it in the boat and it handled it perfectly! Think I have found my new favorite Floro! Like it better than the Invizx so far.
Mastiff 18 lbI bought 3 spools of 18 lb Mastiff. I’ve been using it for flipping jigs and soft plastics, and spinner baits. I’ve been using it for about a month and a half now and been out 8-10 times and caught a bunch of fish on it and it hasn’t failed me yet. Haven’t broke off, haven’t felt any signs of abrasion or nicks in my line. It casts good and flips good. It’s very sensitive. I can feel everything I hit on the bottom with a jig and feel my blades really vibrating with the Megabass SV-3 spinner bait paired up with my Ark Reinforcer rods. I’ve been a Sunline user for many years now and I have to say my personal opinion so far is it’s in between sniper and shooter. It has the manageability of sniper with the sensitivity, strength, and abrasion resistance of shooter. I always use a double uni knot to tie on my baits. Unless I start to have problems for some odd reason it will be my go to line now. Hopefully they end up making bulk spools.
Bad spool? Who knowsI lost 2 jackhammers and an sv3 today because I snapped off casting. I bought the 16lb and was using 1/2oz baits. Was very excited for this line but it’s my fault for going away from invisx.
