How do fish see colour underwater?

the right coloured lure

Image source: lure and light game
Learn to see like a fish and choose the right lure for the job

Every angler has his favourite lure. Entire fishing trips have been spent debating the merits of type, colour and material. So what are the qualities of a great lure? Can we settle the argument once and for all?

In order to find the perfect lure we first need to understand just what it looks like to a fish.
What looks good to us on land doesn’t necessarily look good underwater. It might explain why something that looks drab to us never fails to land a catch; a puzzle blogger Henry Gilbey has long been pondering:

‘It will never cease to amaze me how such a plain and perhaps even boring looking soft plastic lure can be so lethal, and especially when there are so many lovely looking shiny bits of hard and soft plastic out there that look far more appealing both on the shelf and in the water’.

We might think that brightly coloured or iridescent lures are the most attractive but, in truth, a fish may not even be able to see them.

This is because fish eyes have a different anatomy to our own, even though they contain the same basic types of cell: cones and rods. Cones are used during the day, and can perceive differences in colour, while rods only measure the intensity of light, and are responsible for night vision. Fish have almost spherical lenses (unlike our flattened ones), which let in more light, but limit the distance they can see. Many fish have extra cones, allowing them to see more of the total light spectrum than we can. Trout, for instance, can see bits of ultraviolet and infrared light.

This means they can see more ‘colours’ than we can. The extra cones in their eyes are able to detect frequencies of light we can’t. Light travels as a wave, and different wavelengths (the distances between two peaks in the wave) produce different colours. Visible light (the part of the spectrum we can see) is made of different wavelengths, and how objects absorb or reflect particular wavelengths determines their colour. For instance, a red fishing float appears that way because it absorbs all the visible light which hits it, apart from light in the red part of the spectrum. White reflects all light back, black reflects none.

It is easy to think of light as being immaterial, but that isn’t true. It can be affected by the environments it passes through, and this has a big impact upon whether or not your favourite lure is going to catch you any fish today.

While “be the fish” might be a piece of advice too far, it is true that you need to picture the world from the fish’s point of view. Location, weather, water depth, and even season play a role in deciding how effective your lure will be. Wavelengths of light get absorbed by water at different depths – red and orange are the first to go, with violet being the last. So red might work near the surface, but if you’re going deep you’ll want something violet on the end of your line. Uli-Beyer.com have done some extensive research into the effect of water depth on colour reflection and fluorescence (in fresh and sea water), and have found that fluorescent lures can have a marked effect on your results. There are those, of course, who have questioned whether these lures are just a groovy gimmick.

Season and location play a role because they dictate which colours are being reflected into the water. Fish in a pond surrounded by trees with yellowing autumn leaves will be used to seeing yellow and orange in the water. Is it better to choose a lure that mimics those colours in order to fit into the environment, or to go for something out of the ordinary? It depends who you talk to.

coloured lure collection

Image source:River Piker
Match lures to the season, the weather, and your catch

Fish will be able to perceive colours better on bright days, where there is more light getting underwater to reflect off things, than on overcast ones.

So is there a perfect lure? Technically yes, but it depends upon where you are, what the weather is, what time of year it is, and what you are trying to catch. Equip yourself with a varied set of lures to give yourself plenty of options, and you should be able to use the information in this post to better match the lure you use to your fish of choice.