Understanding the Trout’s Feeding Behaviour

The Trout’s Menu:


When considering trout fishing it is important to understand what they eat and when in order to choose the appropriate fly.


Aquatic Insects are insects that live in the water. They have a lifecycle that includes an aquatic nymph stage and then they grow into a winged adult. The adults, who only live for a few hours or days, then return to the water to mate and lay their eggs.


They include mayflies, stone flies, caddis flies, damsel flies, and dragon flies.


Terrestrial Insects are insects that live on the land and become fish food by falling in the water or are gobbled up form low lying growth.


They include ants, beetles, grasshoppers, leafhoppers, crickets, wasps and bees, spiders, and worms.


Crustaceans are an important part of the trout food chain. They generally crawl along the bottom of the water. Freshwater crustaceans include scuds, sow bugs, and crayfish.


Various aquatic bugs are only available or in season at certain times. Fly fishers should try to imitate bugs during their prime periods. This isn't essential since almost any fly can catch a fish at almost any time. However, the truly excellent fly fishing occurs when the trout are taking a certain bug and the fly in use represents that bug. Knowing when to expect those bugs and using a fly to match can significantly improve your odds for some really great fishing.


The behavioural patterns of trout vary significantly between the species, the size and the circumstances in which they are found.


The trout’s habits also change at different times of the day, and again this is dependent on the weather conditions.


Feeding habits and behaviours also change between faster and slower waters of the rivers, and within the lochs and lakes.


Below are only a few of the major aquatic bugs that you will find throughout the fly fishing season, it is not the full catalogue of the larva, nymphs and flies found in fly fishing. To list the full spectrum of them all, it would take another full book of information.


To learn more about the life cycle and lifespan of the aquatic insects, why not buy one of the great entomology or fly tying books from either the internet or from your local tackle shop.


Caddis flies, (or called Caddis, Caddis fly, Sedge) Caddis flies go through the egg, larva, pupa and adult stages.


The first Caddis hatches of the year will vary with elevation but normally start hatching about the last week of May. The numbers and frequency increase until about the last week of June or first week in July and then steadily decrease for the remainder of the season.


Chironomids, (or called Blood Worm, Midge, Gnat) the eggs hatch into larva and form mud tubes from bottom material and mucous. A few species have free swimming larva such as the Bloodworm. Various species of Chironomids hatch whenever there is water free of ice.


Seasonal peaks occur from the third week in May to the second week in June and then steadily decline into the fall months.


Damselflies, (or called Damselfly, Damsel) The adult has four wings that fold over the back. The male of the most common variety is blue while the female is more of a slate colour. For the nymph, a fairly large and bulbous head sits on a tubular shaped body. The eyes of the damsel are fairly pronounced but not as large or pronounced as the eyes of a dragonfly nymph.


Mayflies, (or called Mayflies, Mays, Upwings, Duns, Spinners, Dippers, Fish Flies) 'Hatches' from nymph to sub-imago can begin in the last half of April.


Dragonflies, The main hatches of the dragonfly from nymph into adult peaks about mid July with lesser hatches both before and after that time.


Not to be mistaken for its cousin the damselfly, the adult dragonfly cannot fold its wings along its back. Dragonflies are usually much bigger and thicker bodied than damselflies. Both are very predacious in both the nymph and adult stage. Nymphs will feed on almost any creature in the lake including very small fish.


If fishing is slow, and you see some rises in the shallows, and you have seen some Mayflies, and you are willing to catch the smaller fish, try a dry Mayfly pattern in the shallows. It will often provide some excitement on what could otherwise be a slow day. On occasion, even that larger fish may be taking the dry May.


I have found that instead of studying dozens, even hundreds or more, of insects and the flies designed to imitate them, I've found that in nearly all circumstances, you need only a few fly patterns, each designed to do a specific job in the varying circumstances found on the stretch of water you're fishing.


Trout Flies are used to induce fish to take by the use of recognised food patterns rather than by intended imitation. For this method then, local knowledge becomes relevant in the way the fish are feeding and what is currently on their menu, in this way you can match your imitation fly to the current fly hatch.


Flies can be tied to take advantage of, various aspects of trout behaviour. This opens up possibilities for us to incorporate the use of innovative strategies, tactics and trout fly construction and to give ourselves a far greater edge than previously thought possible.


Normally it takes years of studying these fish, trial and error with different fly patterns, different fishing techniques, different innovative designs and methods with the right focus to get to a place where you understand these creatures adequately for the outstanding results we normally only see the Pro's achieving.



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