Every fisherman needs to know the staples and basics of the trout's diet.
A trout fisherman catches trout by representing in presenting his natural food to him in a proper manner.
Plankton
First, in order to get a good picture of the stream of life which eventually produces a trout, we must start briefly at the bottom of the scale. In every uncontaminated body of water there is a free-floating mass of life composed of tiny organisms so small that they are either invisible or unnoticed by the human eye. A glass full of lake water will contain thousands of such organisms. Billions float and drift near the surface of the lake. By late summer they often become so numerous that in mass they are quite conspicuous; the water becomes tinged or cloudy with them, and the lake is said to be “ Blooming" or “working ".
This society is composed of, first, algae, very minute forms of plant life which convert the energy of the sun into food: and, second, small animals which feed on the planet. Typical of the plans is the diatom. This is the plan which, upon dying, leaves minute skeletons that make up the diatomaceous earth, much use in industry as an abrasive and insulator. Typical of the preying animals are small crustaceans, like Cyclops and Daphnia, or water fleas. Water fleas are well-developed organisms complete with eyes and legs, large enough to be evident except that they are almost completely transparent. In a concentration in a lake or maybe over a million water fleas in a cubic yard of water.
This enormous free-floating mass of life is given the general name of plankton. Small trout feed extensively uncertain of the plankton animals. Some fish, such as Golden shiners, sawbellies, ciscoes, little redfish, alewives, lake herring and lake whitefish subsist almost exclusively on plankton thereby converting this abundant but minute life form into mouth sized trout food. Plankton is so plentiful in the ocean that the largest creatures the world has ever known, that baleen whales, live primarily on it by filtering the minute organisms out of the sea water with the baleen or brush like arrangement in their mouths. The largest of the sharks, the giant basking sharks, also subsist on the tiniest living things. Plankton exists wherever there is uncontaminated water: in the sea, in lakes, in streams.
This plankton, together with water weeds and algae, or green slime, which grow on the weeds in the bottom, form the basis of food, the pasturage, for underwater life. The crustaceans and insects feed on the algae and on each other, and fish feed on the crustaceans and insects and other fish. The more fertile a stream or lake is, the more plankton, algae, and larger forms of life there will be and, of course, the more trout.
Since trout can be caught legally only as they eat, the fishermen would do well to know just what a trout does eat. In the first place a trout is strictly carnivorous; that is feats exclusively on other animal life non-plans as do some fish. The food of trout falls into four classifications: crustaceans, insects, other fish, and miscellaneous foods.
Crustaceans
Crustaceans can form an important item of diet for young trout, and sometimes for the older ones. The crustaceans found in various trout waters include the tiny water fleas, the scuds, the freshwater shrimp's, and the crayfish. The importance of these as food is illustrated by the fact that one female Daphnia, or water flea, might give birth to 13 billion offspring in a period of 60 days. The water fleas are too small and transparent to the imitated by artificial flies.
The scuds insurance are larger, 1/2" or more in length. These are thin bodied semi transparent creatures which are very active: swimming, climbing, jumping, and diving with speed and ease. Some species prefer quiet ponds, but others, such as the Caledonia shrimp, are equally at home in trout streams. The scuds are not so prolific as the water fleas, yet a single pair may produce a family of 25,000 a year. They constitute ideal fish food if they live on herbage and decaying matter and do not compete with trout for insect food. No commercial patterns of flies are tied specifically to imitate these crustaceans, but, rubber scuds makeup and important item of trout food any one of many sparsely tight wet flies finished by the action method the action method make an effective imitation.
Crayfish, or crawdads as they are commonly
called, other largest of the freshwater crustaceans. They are well known to
every fisherman east of the Rockies. This is the favorite food of the small
mouth bass, but as a minor item in the trout's diet. Certainly young crayfish
must be eaten quite often by trout, although I have never discovered one in a
trout stomach. Crayfish are themselves carnivorous and are known to eat their
share of trout eggs and fry. Insects Insects form the bulk of the trout's diet.
All young trout feed primarily on insects. Under certain circumstances, older
trout will turn to a fish diet, but a trout never get so large or exclusive that
he will not eat insects. A trout is continually foraging for food and eating
insects no matter how large he is. When it catches a minnow, it's lucky. It
might have to swallow a hundred insects for an equal amount of food. Yet when
there is a concentrated hatchet insects on, no delicacy can tempt a trout away
from the food at hand. Large trout, small trout, and minnows eat on the hatch
side-by-side, apparently oblivious of each other. Aquatic insects Insects are divided into two groups: aquatic
and land. Land insects form merely an incidental and occasional part of the
trout food. Aquatic insects along to nine distinct orders: Stone flies,
mayflies, dragonflies and damsel flies, water bugs, and net winged insects,
caddis flies, moths, beetles, true flies. These all have a mature, underwater
form, known as larva or nymphs, a mature, ringed forms above water. Some, like
the caddis, pupate in between these distinct stages of life, as does the
caterpillar in his cocoon before he becomes a butterfly. Others, like the
mayfly, emerge as leaned insect directly from the nymph. Fully 90% of the
insects eaten by trout are in the underwater larval or nymph stage. Stone flies
Stone flies are thoroughly distributed through the trout streams of North
America. Like trout, the nymphs prefer cold, running water. They are most at
home in Rapids, and are also found along wave washed shores of lakes. If placed
in stagnant or warm water, they die. They are seclusive in their habits and
live under rocks and in crevices. They will be found clinging to the bottom of
flat rocks which have been picked up from streambeds and overturned quickly. As
soon as a rock is turned over, the nymphs scurry off to the sides and dropped
back in the water. Small mayfly nymphs and caddis fly larva may be found under
the same rocks. Adapted to this life under rocks, the
stonefly nymph is flat bodied with legs that protrude horizontally out to the
sides. He looks like a bag that has already been stepped on. The various
species ran in size from half inch to 2 inches. Some are black in color, others
like the most common species, are mottled with a brownish green and yellow
design. I'll have two conspicuous tales and two long feelers. Continued on next
Trout Food page Excerpt from “The Trout Fisherman’s Bible”
by Dan Holland copyright 1964. Please send questions, comments, local fishing info and stories to
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