Fishing Lure Color & Depth

What colour of lure can your fish actually see, at this depth, in this water? Every angler has read the chart: red dies at 5 m, chartreuse for muddy water. Those charts are drawn for one imaginary lake. Lure Depth computes the answer for YOUR water, YOUR depth and YOUR target species, from published underwater optics and measured fish physiology. And it will tell you when the honest answer is "colour is not doing any work here". ■ WHAT YOU GET • A ranked lure table. Tell it which colours are in your tackle box and it ranks them by how much each one stands out to your target species, right now, with an estimated distance at which the fish can detect it. • A live camera. Point your phone at a real lure and see it as a bass, a pike, a trout or a tuna would see it at depth. Hold anywhere to compare with the unfiltered view. • Target species, freshwater and salt: largemouth and smallmouth bass, brown and rainbow trout, northern pike, muskellunge, walleye, zander, perch, carp, roach, tench, barbel, wels and channel catfish, eel, sturgeon, tilapia, peacock bass, snakehead, Atlantic salmon, char, seabass, seabream, striped bass, red drum, spotted seatrout, cod, pollock, hake, turbot, halibut, bonefish, snook, tarpon, barracuda, meagre, dentex, bluefin and yellowfin tuna, skipjack, mackerel, mahi-mahi, sailfish, blue marlin, swordfish, amberjack, yellowtail kingfish, bluefish and blue shark. • 19 water types. Jerlov's oceanic and coastal optical classes for the sea, plus nine freshwater presets from gin-clear to a river in flood — tannic, blackwater, algal bloom, stained, muddy. Match yours with a Secchi reading: drop a white plate on a string and note where it disappears. • Lure colours with real finish models: matte, gloss, metallic, translucent and fluorescent. Green pumpkin, watermelon, junebug, black and blue, chartreuse, firetiger, sexy shad, blueback herring, bone, chrome, gold, clown, sardine, mackerel, bonito, ghost minnow and more. ■ THE PART NOBODY ELSE MODELS Murky water does not just block light. It GLOWS — suspended particles scatter light back at the fish like fog lit from within, and that haze is what really kills contrast. Every depth-colour chart on the internet models the light going down and none of them model the haze coming back, which is why they all overstate how far a lure can be seen. Lure Depth models both, using Duntley's contrast law. It is why the app will sometimes tell you a bright lure is invisible at two metres. ■ IT WORKS OFFLINE Completely. No account, no signal, no server. You fish where there is no coverage; an app that needs the network on the boat is dead weight. ■ CONDITIONS ARE ALWAYS FREE Every water type, every depth, every light condition and every viewing angle is free and complete, permanently. Capping the physics would make this a toy. Only the species catalogue is paid: €0.99 for one species forever, or €4.99 a year for all. Four are free forever. ■ WHAT THIS APP DOES NOT DO It does not promise you a catch. Nothing can. It models the physics of light and contrast underwater — whether a fish can tell your lure apart from the water, which is necessary for a strike but not sufficient. It models no fish behaviour at all. It also gives no advice on fishing regulations. Size limits, closed seasons and quotas vary by region and change without notice. Check your local authority. ■ THE NUMBERS ARE SOURCED Jerlov's optical water types. Pope & Fry's pure-water absorption. Duntley's 1963 contrast law. Govardovskii's visual pigment templates. Lythgoe's Ecology of Vision. Aksnes & Utne's fish visual-range model. Hart's demonstration that sharks are colour-blind. Most fish have never had their visual pigments measured. Rather than invent a curve, every species carries an evidence grade — measured, close relative, same family, or estimated — and it is shown on the card, not buried in a footnote. Three species have no spectral data at all and say so in the strongest terms available.