Popular Science Monthly/Volume 47/October 1895/Trout Culture
| TROUT CULTURE. |
By FEED MATHER.
IN the early days of fish culture, which for many years was only trout culture, the statement was often made that any farmer who had a small spring of cool water could, within a few years, realize enormous profits from it, and that an acre of water was worth more than an acre of land. Those of us who went into the business a quarter of a century ago found much to learn, and many dropped out discouraged. The writer bought a farm in Monroe County, New York, in 1868, and made ponds below a fine spring; and after some failures, due to ignorance for there was then no literature of the subject—he began to succeed in raising many fish, only to find, after raising them, that they had cost more than they were worth, because there was no available food near, and it required a man to drive fourteen miles to the city of Rochester twice or more per week for food. To-day we know that something more than a good spring of cool water of about 50 F. is necessary, and also that some acres of water may be worth more than some land, but that so many local and other conditions enter into the calculation that, as a general statement, the comparison is not true. To-day there are several successful trout farms where the fish are raised for market at a profit, and in all of them there are large, never-failing springs of cool water and cheap food, as well as intelligent management. There are other important considerations in choosing the location of a trout farm, such as a proper amount of fall to the water in order to control it and give it aeration between the ponds and a formation that will allow all surface water to be led aside and not to enter the ponds. A sudden thaw with frozen ground may destroy the work of years, and in summer the surface water brings leaves and trash, which clog screens and either burst or overflow them.
The first thing to be considered is whether the trout farmer wishes to merely hatch his fish and turn them into a suitable lake or pond where they will find their own food and where he can take a few for sport and market, and perhaps let anglers fish it for a fixed sum, or whether he prefers to raise his fish by hand in small pools.
The first method is the simplest, involving the least care, but, if the conditions are favorable, not so profitable as the other. One is like keeping a few fowls that pick up what they can, and the other like poultry breeding, with this exception: poultry will not eat their young, while trout will devour their fellows which are smaller. A trout under a year old feeds mainly on insects and their larvæ in a state of nature, but a large trout of two pounds weight prefers something more substantial, like a yearling trout or two for breakfast and a few more at intervals, with flies and worms for dessert; and this cannibalism is what keeps the 
Stripping a Small Trout. balance of life in a natural state. If, however, it is decided to follow the first-named system, it will only be necessary to provide spawning races for the adults and follow the rules for hatching the eggs, and either turn out the product as fry or as yearlings; the latter will give the best results where transportation is not needed, as in the work of the fish commissions of the different States.
Where it is desired to make a business of trout-raising a series of small ponds are necessary. After leaving the springs the water, in summer, is continually approaching the temperature of the air; and when it gets to 70° the danger line is reached. In swift water our brook trout have lived at five degrees above that point, but they suffered, and some have died, while others lived until the declining sun permitted the water to cool a trifle. This is a point that should be in mind when planning ponds, for it is of the greatest importance. A spring brook that will sustain many trout in a pond of half an acre might fail to keep a single one if the area was doubled. The surface and the shallows are warmer in summer than the deeper portions, and in the case of springs in the bottom of lakes or ponds the trout will gather about them in warm weather. In the pond system the ponds are so small that the fish can be seen at all times and their growth noted, so that those which have outstripped their fellows may be taken out and placed with others of the same size. This is practiced once a year with the larger fish and about three times during summer with the "babies," or those not yet arrived at the dignity of yearlings. Cannibalism is not only prevented by this, but the smaller ones will have a chance to get food at the first table, from which they have been debarred.
Perhaps a description of the ponds that I have made for the Fishery Commission of the State of New York at Cold Spring Harbor, Long Island, may best illustrate the idea of small ponds, first explaining that the object of the ponds is not only to grow trout, but to get the greatest amount of eggs for hatching in order to stock public waters with the different species of trout, such as our native brook trout, the brown trout, or common brook trout of Europe, and the rainbow trout of California. The trout for distribution are sent out when about ready to take food—in March and April. Those to be kept at the station for breeders are fed in the troughs for a month or more, and are then put in the "baby ponds." These are of two-inch yellow-pine sides and one-inch bottoms, twenty-five feet long, three feet wide, and about twenty inches deep, with a strong flow and double screens of No. 8 wire cloth, between which is a dam an inch higher than the pond below. In these ponds are "rests," made of projections from the sides or of dams, with a surface stop-water a few inches below them, which causes the water to flow up and over the dam, and is then again deflected below. This keeps weak fish from being swept against the screens, and makes eddies for the food to swirl about in, instead of sinking. Mr. Hoxsie has patented an ingenious device to
Trying the Big One without Help.
feed young fish in, and it is somewhat different from this plan which I used at Honeoye Falls, N. Y., in 1874 and since. Of these "baby ponds" we have ten, and, as we put ten thousand fry in each, we start in with only three of them stocked; but the little fellows have a way of getting around screens that are supposed to be tight, and before they are an inch and a half long some are found in the lower ponds, having gone through joints in the planks or sides or bottom, or around some loose screen, if not through a neglected worm hole or nail hole. Their persistence in getting out of the place where they are put is wonderful.
When the fish are about six months old, say in September, they are taken out of the baby ponds, assorted in three or four sizes, and put in the yearling ponds, where they remain until the following year, when the largest are sent to the breeding ponds. At the same time the water is lowered in all the ponds, and they are thoroughly swept out preparatory to the taking of spawn, and the fish are not again disturbed until spring. The breeding ponds are cleansed in this way in midsummer, but all are daily gone over with long-handled nets to remove the ordure and any uneaten
When a Large Trout Struggles.
food; the screens in the baby ponds are not taken out, but are cleaned with brooms or a scrubbing brush on a handle.
The breeding ponds are best if about sixty feet long, fifteen feet wide, and from two to three feet deep. In such a pond from one thousand to four thousand trout of half a pound may be kept if the flow is sufficient. If the supply of water is scant in summer, make the pond narrower or shallower, in order to give a quicker change to the fish.
Each breeding pond must have a spawning race at its head, and these are narrow and shallow, making an ideal place for a trout to deposit its precious burden. They are from twenty-five to fifty feet long, two to three feet wide, with water from five to ten inches deep. The bottom is covered with gravel of the size of a pigeon's egg, and the top with boards cleated together in convenient lengths to lift. Here are all the requisites of a nesting place—swift, shallow water, gravel, and shade, with its security from overhead enemies and light. If undisturbed, a {>air of trout would whip a nest in the gravel and lay their eggs and retire after covering them, and the next pair would whip them out again in their efforts to perpetuate their species, and in a state of nature a horde of yearlings would follow the breeders to feast upon the eggs, for of all fish baits the eggs of trout and salmon are among the best. The spawning race is only to entice the trout to spawn there; a net on a frame sliding into grooves at the lower end is slipped in, the covers lifted, and the fish driven into the bag. They are then assorted. Those not ready to spawn to-day or later are thrown back into the pond, the ripe males are put into one tub and the ripe females in another, and to judge of this we note the swollen vent and the softness of the abdomen. This is the first test; the next is the ready flow of eggs.
Here it may be well to say, in nature not more than forty per per cent of the eggs are impregnated, owing to the failure of the milt to reach all the eggs. Of those that are impregnated fully one half are killed by the fungus that grows on the dead infertile eggs, and the remainder are subject to suffocation from freshets, depredations by young trout, eels, ducks, and other animals, as well as the sun, while in our so-called artificial propagation we get such a close contact of milt and eggs that the impregnation amounts to about ninety-five per cent, and there is no loss from sediment, fungus, enemies, nor direct sunlight. There is a loss of perhaps five per cent in deformed fish, such as crooked tails, double heads, twins with one umbilicus, and premature bursting of the shell, but we beat Nature in trout-hatching far more than we do in the breeding of any other animal, and the only comparison that seems fit is' that of cultivating trees and plants, where we produce more than Nature can or does.
Our brook trout usually spawn from November to January on Long Island, in the early part of the day, while the lake trout, improperly called "salmon trout," spawn at night, thus preventing hybridization by means of drifting milt. About 8 a. m. we place a net at the foot of the spawning race and drive the fish that have run up for nesting into it. They are then put into tubs and assorted. The males are put together; the females that appear to be ripe are placed in other tubs, and those which are not near ripe are returned to the pond. A ripe male is known by its slim body and bright color; often his back will be buff, the sides scarlet, and the lower abdomen with a black stripe on each side. The ripe female is soft, and the vent is swollen and protruding. Unless the eggs flow at a light touch, it is better to return her to the pond, for eggs that have to be forced are not ripe, and if they can be fertilized make weak fish. For the manner of handling the fish, see illustrations from photographs. The so-called "dry method" is the best. A pan is wet and the water drained from 
Lower End of Hatching Trough. it. The eggs of a female are taken by repeated strokes of the forefinger, if the trout is small, or by the hand if large. The eggs will be found to lie the full length of the body cavity, and the strokes begin near the vent and are then worked farther up toward the head. A bending of the back, as shown, often starts the eggs. This operation takes less time than it does to write it, and some water drips from the fish. A male is then stripped over the eggs and water enough to cover them is added, after which they are left to stand until they "free." The eggs are soft as they leave the fish, and for twenty minutes or more they absorb the milt and water, and while doing this they adhere to the pan, but become free when filled. They should not be disturbed until free, when they are washed by changing the water and then are placed on trays in the troughs. If an egg is not impregnated before it fills with water it never can be fertilized, and the advantage of this "dry method" over taking the eggs in a pan of water is that each egg is brought into contact with the milt, which suddenly becomes active when it comes in contact with water.
This work and all troughs should be in a building and protected from storms and sunshine, but hatching troughs have been successfully worked in the open air. Rats are fond of trout eggs, sediment will smother the embryo within the shell, and direct sunlight will kill it. In a hatching house a distributing trough should run the length of one side. If this is ten inches wide and nine inches deep, with occasional cleats on top to prevent spreading, it will be about right. The water may flow in at one end and out at the other, over a dam six or seven inches high. With hatching troughs at right angles to this and supplied by inch-and-a-half cocks or gates the flow will be regular at all times. These cocks should be halfway between the bottom of the distributing trough and the surface of the water, and may have a fine screen above them, or may pour into one below, as seems best, always looking out that the flow is not stopped nor any fine material enters the trough that would clog the screen at the lower end of the hatching trough and cause it to overflow and the fry to escape.
These hatching troughs are best made of soft wood, preferably sound, clear white pine, and if possible have them up so that the tops are three feet six inches above the floor, for convenience in working over them. If the bottoms are an inch and a half thick, three carpenter's horses will sustain them. A trough thirteen feet long, fourteen inches and a quarter wide, and seven inches deep, inside measure, will be sufficient for twenty-five thousand trout fry after they are hatched and feeding, but will be capable of developing four times that number of eggs. The troughs should be made of regular width, to a hair's breadth, in order to have any hatching tray fit every trough in any part of it, and the edges of the bottoms should be carefully dressed and the
Lower Ends of Troughs with Outlet Pipes.
sides nailed to them after being touched with thin white lead. The ends should be let in (see cut), in order to be nailed both ways and be tight. An inch-and-a-half hole in the bottom of the lower end will take the waste water where required; a sink outlet with the cross-pieces cut out is good to attach a waste-pipe to; above this hole nail an upright strip to each side to hold the dam. During the egg stage use one of two inches or less; after hatching begins, put in one of five inches and a screen above it. Just above the dam put two strips each side to hold the screen, which must fit tight all around, or tails will get in cracks and the fish will die. This screen should be of No. 14 wire cloth, and is sometimes placed upright and at others with its top up stream to give more surface and to release a weak fish from it by its own weight, but the difficulty in keeping a screen so placed clean is an offset to its advantages. If space permits, the troughs should be placed by twos, but some prefer them by threes.
Coal Tar.—All troughs, screens, trays, and all wood and iron that is in contact with water, should be painted with coal tar, which can be had from the gas-works. Thin it with spirits of turpentine, and give it two or three coats with a half-worn painter's brush in hot weather. It must be perfectly dry before water is let in, and then there will be no taste, rust, flavor of pine, nor fungus. Asphaltum is used, but I have not tried it. After the first season one coat each year is sufficient.
If the hatching troughs are all exactly one width, make the trays one quarter of an inch narrower and about twenty-seven inches long; use half-inch pine, cut in strips three quarters of an inch wide and laid flat, so that the frame is only half an inch deep; make the corners strong. If the frames are fourteen inches wide outside, have wire cloth especially woven of a length to cover them all, but half an inch narrower than the frames, for the selvage will be uneven; have it made with a mesh three quarters by an eighth of an inch, the long way of the mesh across the cloth; this holds the egg, but lets the fish drop through. Use No. 18 wire for the cross-wires, and finer wire for the double over and under, for the warp. A double-pointed carpet tack under each corner of the tray allows circulation beneath and prevents crushing the fry.
Having shown how to make the troughs, screens, and trays, and how to take the eggs, we must now proceed to the care of the eggs and fry. Our implements are few and simple: a wisp broom, a pair of nippers, a small, flat net, and the wing-feather of a goose set in a handle of light wood are all, except an outfit of pans which are to be used in stripping the fish. The little hand broom is used daily; a tray of eggs is taken from the bottom of the trough and soused in and out of the water to remove sediment, and is put over into the next trough, etc. When all are out, the dam below is removed and all slime washed out and both darn and eggs replaced. The nippers are cut out of wood, red cedar preferred, and are about six inches long, with a spread of three quarters of an inch at the points; the latter are best when finished with a loop of brass wire, but can do good service without this. A dead egg turns white, and can be seen at a glance among the amber ones, and an egg that has not been fertilized often remains clear until the rest are nearly hatched, but it can not stand any rough usage, and shows up in numbers after each washing, and, if left for two or three days, will develop a fungous growth that will attach the surrounding eggs in a mass and kill them all. In our early work, when we hatched on fine gravel, fungus was the bugbear: a dead egg would get down in the gravel and send out its deadly tentacles unseen; but with wire cloth and daily supervision fungus is unknown. It is this that kills the eggs in the brooks, and avoiding this cause of mortality from
Front of Hatchery, showing Inlet Trunk from Reservoir.
By courtesy of Mr. W. H. Cooper, President of the Photo-Section, Brooklyn Institute
unimpregnated eggs is one of the reasons why we beat the methods of Nature in increasing a species by protection from its enemies.
At about fifteen days old the expert can take trout eggs in a glass tube or vial and, by holding them above his eye, can see the line of vertebrae which marks the impregnated egg; a few days later he can pick out the "ringers," or eggs which, having no fish in them, retain the ring which they first had on top of the egg. At thirty days, more or less, according to temperature, the eyes show, and the development goes on until the hatching begins at sixty to ninety or more days, according to the thermometer, but the colder waters produce the strongest trout.
When hatching begins, the water in the trough is raised, and the trays are brought near the surface and held there by light wedges which do not spring the sides of the troughs. The feather sweeps the bottom of sediment, taking care not to injure the delicate embryos, for they are more delicate when first hatched than when in the egg. At this time cleaning should be confined to the removal of any dead eggs or fry and of egg-shells on the screen, and here is where the little flat net of milliner's "millinet," on a three-inch brass-wire frame, is found most useful. This wire is covered with muslin to which the netting is sewed, and, moved quickly through the water, it gathers the shells which are clogging the screen, and a smart rap on a pan cleans the net. It is also of use in taking out dead fry and foreign matter from the bottom, as well as deformed fish, for we find crooked-tailed fish that can not swim and take food, double-headed fish, and twins attached to one sac, which never live.
When first hatched the embryo trout hardly look like fish; they have simply burst the shell in which they appeared as a slim, dark body, with big eyes, coiled around the yolk, and now merely straighten out and have the great yolk-sac still attached, and so heavy that they can not swim, but lie on their sides and huddle together to avoid light; and now there is danger of the bottom ones being smothered. Cover the trough in spots to induce them to gather in different places, and keep them as dark as possible. At this stage there is nothing to do but to remove the few dead sediment can not hurt them now—and keep the outlet screen free. When they get to be about a month old the sac will be nearly gone, and the fry begin to show signs of swimming by occasional darts from the bottom to examine some floating particle. They will take food some days before the sac is absorbed, and it should be offered to them in small quantities.
The best food that I have found is beef liver, after abandoning it for soft clams (Mya arenaria) salt-water mussels, and horse meat. The clams made the young fish grow fast, but did not produce the expected number of eggs; the mussels were tried raw and cooked, with the same result; and, as the principal object at this State hatchery was the production of fry for planting public waters, we. next tried raw horse flesh, which was very objectionable on account of the large proportion which was passed undigested and clogged the screens and fouled the water. Several fish culturists have found an admixture of bran, shorts, or mill feed with liver to be excellent. This I have not tried, because the trout is not a vegetarian in the least degree, and it remains to be proved that such vegetable addition to the food is of real advantage.
The liver is fed raw; for the "babies" it is run through a 
Rearing and Breeding Ponds at Cold Spring Harbor, showing Sunshades and Spawning Races for Large Ponds. By courtesy of Mr. W. H. Cooper, President of the Photo-Section, Brooklyn Institute.
meat cutter having holes one thirty-second of an inch at first, the holes increasing in size as the fish can take larger particles. This is mixed with sufficient water, and little by little scattered along the troughs from a wooden spatula, taking care not to feed so much at once that it will not be eaten. With twenty troughs one man should feed all day, getting back to the first one in half an hour, for, like all small animals, the trout want but little at a time, but want it often. For this reason I never advise a novice who receives fish from the State to pen them up and feed them; they would surely be starved, for if the. young are not fed a dozen times a day they will show it by a shrunken body which appears to be all head. A trout at two to three months old should be larger around the abdomen than about the head, and there should be no pinched look behind the gills. If you can not give the babies this care, turn them into the stream or lake, and let them find their food and face their enemies, and you will have more and better fish. To take trout eggs and hatch them is not difficult, but the best trout breeder is the one who brings the greatest percentage of what he has hatched to be thrifty fish at six months old.
For the yearling trout the liver may be cut in pieces from a quarter to half an inch, and they should be fed all they can eat at least twice a day. Larger fish will take more and larger pieces, and will get along if fed once each day, preferably in the evening, but they do not suffer if neglected for a day as the babies do, and we find the same rule all through animal life in mammals and birds, with which most people are more familiar—the young require frequent feeding.
Too much importance can not be attached to the feeding of the fry in the early days of their taking food. It is the critical time, not only of their lives, but of their future development. No amount of feeding can make a thrifty fish of one which has been stunted by scant food in its first few months of life, and right here is where intelligent care turns the scale between profit and loss.
During the quarter of a century in which I have been engaged in this work, and have had to trust the care of the fish to employees because my own time was fully occupied with other work, the man most valued was he who took best care of the babies and fed them as though he loved them, and not in the spirit of one who did it as a task.
If one wishes to raise trout on artificial food he must bend to the task as he would if he were to raise any other stock in quantities in confined quarters; but he can arrange natural spawning races, and either take the eggs by hand or let them be laid by the fish, and be satisfied with a much less number of fish hatched, and then let them take care of themselves in a large pond or lake of suitable temperature, and, if the water is not infested with sunfish, perch, and other enemies which are beginning to look for food in the spring when the young trout is also looking for its first food, there is every prospect of success.
