Water clarity and colour choice

Clarity doesn’t make colour “more important” or “less important” — it changes exactly what the fish’s eye manages to read: shade, contrast, or only the outline.

Clear water: everything shows, including what shouldn’t

When the Secchi disc reads two to three metres, a lure is visible from far away and for a long time. The fish has time to study the colour, the shape, the leader, and the knot. Here it’s resemblance to forage that wins, not brightness — every mismatch costs more.

Turbid water: only contrast is left

At half a metre of clarity, shade no longer registers — what registers is a dark shape on light or a light shape on dark. That’s why extremes work in murky water: solid black and acid brights, not delicate natural tones. Black is no worse than bright here: against a light background it’s the more contrasting choice.

Size registers before colour does

At the limit of visibility, only a shape without detail shows, and the first thing a fish knows about it is size. That’s why in murky water the lure is sized up before the colour is changed: a bigger shape is visible from further away at the same shade.

Tannin-stained water: colour changes on its own

Brown bog water passes the yellow-red part of the spectrum and blocks the blue. A lure that’s blue on the shelf looks almost black in such water — and that’s not the lure’s fault but a property of the water. Buying a colour in the shop and checking it on the water are two different things.

Depth works the same way

Going deeper affects colour the same way murk does: the spectrum gets cut, just in a different order. What disappears first, and why, is in the card about fish vision.

When colour stops deciding anything

At night, in heavy murk, and at depths beyond the reach of light, every option gives the same result: a silhouette. Arguing about shade is pointless then, and what matters is size, profile and vibration.

How to check on the spot

Lower any light-coloured object into the water — a metal lure, a lid, your hand — and watch the depth at which it disappears. That’s a field Secchi disc; you don’t need a hydrologist’s precision, just the order of magnitude: centimetres, half a metre, or metres. On a river it’s also worth checking upstream — murk arrives from above and reaches a lower stretch later.

What we don’t write here

We don’t give a table of “water like this — colour like that”. Such tables circulate on forums and on packaging, but there’s no reproducible study behind any of them, and every water body has its own water.