About the lab
Fish Hook Labs is the Rig Studio: a browser workbench where you assemble a complete setup one component at a time and watch a compatibility engine check the whole thing as you go.
Most tackle advice is delivered as a list. Five hooks, three lines, a winner and four runners-up. That format hides the only thing that actually decides whether a rig holds: how the parts relate to each other. A hook that is right for one species on 30 lb braid is the wrong hook on 6 lb mono in gin-clear water, and no ranked list can tell you which situation you are in.
So the unit of work here is the build, not the product. You pick a target species and a water type, then work down through hook, beads, swivel, weight, float, leader, mainline, reel, rod, bait, storage, apparel, waders, vessel, and on-water tech. Every selection is re-checked against every other one, and problems surface the way they do in a code editor: a severity, a one-line message, and a detail pane with the numbers.
errorSwivel rated 35 lb under 40 lb mainline
Any rig fails at its lowest-rated component. Right now that is the swivel, which means a hard hookset costs you the entire terminal end including the hook and weight. Rule of thumb: swivel rating at or above 1.5× your line test.
rules.ts — swivel-weak
People who want the deep dive. If you are the kind of angler who reads the spool label, who wants to know why a fluorocarbon leader is being suggested rather than just being told to buy one, and who finds a stated threshold more reassuring than a confident recommendation, this is built for you.
That includes beginners. Depth and difficulty are not the same thing. A new angler handed the sentence "your bead bore is smaller than your line diameter, so the rig will bind" has learned something durable. The same angler handed "buy this bead" has learned nothing and will make the mistake again with a different bead.
When the engine flags a problem it prints the two numbers it compared and the margin between them. A warning is never "this seems off" — it is "0.9 mm bore against 0.86 mm line, and you need 0.15 mm of clearance". If you disagree with a threshold you can see exactly which one to disagree with.
Ranking inside the component picker is spec matching against your build and your target species. Commission rate, price, and whether an item even has an affiliate link are not inputs to it. The code that scores parts and the code that builds outbound links do not share any state.
There is no "our top pick" badge overriding the sort, no sponsored slot, and no interstitial that has to be dismissed before you see the list. If a $4 hook clears every rule and a $19 hook does not, the $4 hook sorts above it.
The engine works from published specs and species tolerance windows. It does not know your local regulations, the water on the day, or how far you can actually cast. Where it is blind, it says so rather than guessing confidently.
The compatibility engine is a set of rules over published specs. Each rule compares numbers that are printed in the inspector next to every part: line test and measured diameter, swivel breaking strain, bead and sinker bore, hook wire gauge and gap, rod line and lure ratings, reel drag and capacity, float buoyancy. When a rule fires it names itself, so a given warning can be traced to one comparison rather than to an opinion.
Where we have judgement rather than a measurement — a species tolerance window, a rule of thumb like 1.5× line test on a swivel — it is labelled as a working window and the reasoning is written out. You are welcome to override it. The studio will keep showing the warning and will keep letting you build.
The full write-up of how gear enters the catalog and how the rules are structured is on themethodology page. How the site makes money, and why that is structurally separate from the engine, is on theaffiliate disclosure.
Specs get misprinted, manufacturers change them silently, and rules of thumb are arguable. If a number in the catalog is wrong or a rule fires when it should not, tell us and we will fix it or explain why we think it is right. Both outcomes are useful.Contact and correction details.