Mike Ladle

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Tackle and Tactics.

THINK LIKE A FISH Part 16 What colour is a fish?

What colour is a fish? A simple question but not so easy to answer as you might think. Just take an example. Look in any text book of British Fishes and you will see pictures of those (now) rare and exciting fish the shads. Now shad are relatives of herrings and sprats and they could easily be mistaken for decent sized herrings. The features used to identify shads relate to things like the number of gill rakers and similar obscure details. However, the book will show you that shads - unlike herrings - have dark spots, a bit like fingerprints, on their flanks. The Allis shad which is seems to be almost extinct in our rivers has one spot and the Twaite shad has a whole row of spots. What the book will fail to tell you is that the spots disappear as soon as you lift the fish from the water and, like magic, reappear when you pop it back in. It's a bit like those holographic images which only appear when you view them at the correct angle.

So there's the first problem, fish in the water may look different to fish 'in the hand'. An additional difficulty, and one well known to sea anglers is the way that the colours and patterns of fish rapidly change and fade as they die. A black bream or a pouting fresh from the sea will usually have dark vertical stripes on its body but within minutes of being lifted into the boat the markings will have gone. These changes are quite different to the 'pressure patterns' that appear on the bodies of cod, conger and other fish as they lie in the fish box or on the bottom boards of a boat.

Even more transient are the fantastic violet sheens that overlay the bright silver scales of living salmon, sprats and many other near-surface swimmers. These interference colours may last for only a few seconds after the fish is caught so only a sharp eyed angler is ever likely to see them. Other species may have green or gold iridescent overlays on the basic silver and still others seem to be all colours of the rainbow. The skin of a living mackerel, for instance, looks as if it was covered with a thin film of oil constantly changing colour as the fish moves its body from side to side.

Some colour patterns have very obvious functions such as camouflage or display. Most bottom dwelling fish are broadly coloured like the sandy or rocky seabeds over which they roam and many have a mottled pattern or disruptive markings that break up the 'fishy' outline. In addition most fish are able to change colour so that even silvery surface dwellers like herring, bass and mackerel may adopt different shades in dirty water or poor light. The past masters of colour change are flatfish which are often able to match almost any sea bed in a matter of seconds.

The contrasting spots and brightly coloured markings of some wrasses, breams, dragonets, gurnards and the like are clearly for displaying to the opposite sex or for bullying rivals. The bigger and brighter the pattern the better it tends to work. However, there is a drawback to this flamboyant display. Any fish that is unusually conspicuous is more likely to attract the attention of a predator. It's all a matter of swings and roundabouts.

A relatively recent discovery are the 'hidden' display colours of fish such as mackerel and, particularly, scad. In the hand scad or horse mackerel are essentially shiny green and silver in colour. The bright silver flanks conceal red and yellow interference colours which are displayed to other members of the shoal as the fish turns, allowing the fish to synchronise their swimming. Scad also have another trick. Inside the mouth is a bright shining white disc which is only apparent to other members of the school when the fish is feeding. This seems to be a sort of dinner gong or 'come and get it' signal.

Interestingly scad are attracted to lights and may feed right at the surface under street lamps on bridges, promenades and piers. This, and their preference for plankton and other small food items, makes them prime candidates for nocturnal fly-fishing. Experiments have shown that whiting also have a fatal attraction to lights at night time so it may not be long until we see anglers wielding fly rods from the winter beaches.

If you have any comments or questions about fish, methods, tactics or 'what have you.'get in touch with me by sending an E-MAIL to - docladle@hotmail.com

INFORMATION SPOT

Think like a fish.

What colour is a fish?.

A twaite shad.

A 'fly' caught shad.

Fly anglers after scad.

Steve Binke landing a scad.

A modest, fly caught, scad.