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AN IMPROVEMENT IN HATCHING AND REARING
BOXES; WITH NOTES ON THE CONTINUOUS
FEEDING OF THE FRY OF SALMONID/E # #

From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908

Proceedings of the Fourth International Fishery Congress : : Washington, 1908

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WASHINGTON : : : : : : GOVERNMENT PRINTING OFFICE : : : : : : 1910

BUREAU OF FISHERIES DOCUMENT NO, 704
Issued April, 1910

APR 15 1910
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AN IMPROVEMENT IN HATCHING AND REARING BOXES;
WITH NOTES ON THE CONTINUOUS FEEDING
OF THE FRY OF SALMONID/L

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By G. E. Simms

£x-Curator of the Brighton Aquarium, Brighton, England
ed

Paper presented before the Fourth International Fishery Congress
held at Washington, U. S. A., September 22 to 26, 1908

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AN IMPROVEMENT IN HATCHING AND REARING BOXES;
WITH NOTES ON THE CONTINUOUS FEEDING
OF THE FRY OF SALMONID£.

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By G. E. SIMMS,

Ex-Curator of the Brighton Aquarium, Brighton, England.

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It will, I think, be admitted by even the most conservative exponent of
modern pisciculture that there is ample scope for improvement in the type
of box now used for hatching and rearing, inter alia, the eggs and fry of
salmonoids. Speaking broadly, it appears to me that it would be impossible to
conceive and, having conceived it, to design an appliance which so thoroughly
combines in a small compass the minimum of utility and the maximum of
imperfection characterizing the square cornered, oblong pattern of wooden box on
which pisciculturists, for lack of a better form of apparatus, are forced to depend
for carrying out one of the most important sections of their work. It is not
improbable that this may be regarded as a too sweeping indictment of an old
and valued servant—if I may be permitted so to describe an inanimate
object—but, at the risk of differing from those of my hearers who later on will
be my critics, I venture to maintain that, apart from the fact that by its agency
fish ova can be brought to maturity, the rectangular wooden hatching box has
not a single redeeming quality attached to its name. Indeed, so much so is
this the case that I will advance a step further and assert that any utility
it may possess in this connection is altogether nullified by the facilities it
provides for the unchecked production of fungus, which render it a constant
menace and danger to eggs, alevins, and fry alike, so long as they are confined
within its sphere of influence.

Three factors are responsible for this unsatisfactory state of affairs. These
are the material of which the box is built, its rectangular form, and, last but
not least, the position at which the waste-water outlet is situated. A moment’s
consideration will convince anyone with a practical knowledge of the interior
of a hatchery of the correctness of my statement. From either a practical or a

1017

1018 BULLETIN OF THE BUREAU OF FISHERIES.

scientific point of view, wooden appliances leave more to be desired than they
give. Not only are they heavy, unwieldy, and liable to leakage at odd and
inconvenient moments, but they have the additional disadvantage of becoming
water sodden and readily receptive to the spores of fungus. With the object
of preventing any possibility of attack from this, the pisciculturist’s most
insidious enemy, the services of the charring iron are brought into requisition
to antisepticize the interior of the box.by superficial carbonization. A more
brilliant method of holding in check an ever-present evil of any kind has seldom
or never been devised. The only fault that can be found with it is that when
those parts of the box which have undergone carbonization are subjected to
the action of water any antiseptic properties they may have possessed while
dry rapidly disappear, and in a short time the last state of that box as a fungus-
fighting appliance is worse than its first. The mischief does not, however,
end here. In the course of a few days the inside of the box up to water level—
assuming, of course, that it is in use—becomes covered with a viscid slime, and
this, in conjunction with the roughened, semispongy substance of the carbonized
wood, forms a secure resting place on which particles of excrement and of
unconsumed food, as the case may be, can decompose and generate a more or
less plentiful crop of fungus.

Turning to the form of the box, what do we find there? The supply, whether
it falls in from above or is so arranged that it enters from below, has to force
itself against the whole volume of the contents of the box, and consequently
its force is expended and ceases to make itself felt before it has, at the outside,
reached more than 3 inches from its point of entry. In other words, it is
absorbed into and assimilates with the water into which it is poured instead of
forming, as it should, a gentle current running over the eggs from end to end
of the box. This raises a question as interesting as it is important scientifically
and commercially, viz, are the eggs under conditions such as these, which in
no wise conform to natural conditions, properly oxygenated by the water in
its upward progress toward the outlet? Furthermore, is the passage of the
water from the inlet to the outlet equal or intermittent? In regard to each
I hold an opinion which is not an affirmative one, but I leave the definite
solution of this very interesting problem to those who have more time and
opportunities at their disposal than I have for carrying out the necessary
experiments.

No doubt many of you have watched a pair of trout making preparations
for spawning, and as you have watched you have wondered at the marvelous
instinct which prompts the male fish to select a point above the redd, i. e., the
spawning bed, with just sufficient stream to carry the milt as he discharges it
in a milky cloud over the eggs which have been deposited by his mate. But
the two fish—and to the lady must be accorded her fair share of credit in their

AN IMPROVEMENT IN HATCHING AND REARING BOXES. IOIQ

joint undertaking—have a much deeper purpose in view than the efficient
impregnation of the eggs alone. Their instinct also teaches them that the eggs,
without an adequate supply of oxygen, will not come to unimpaired maturity,
but will produce weakly alevins, and that unless a current of water passes over
the eggs while incubation is proceeding they will not obtain a requisite amount
of oxygen. Here it appears to me that the dumb instinct of the fish is far
superior to the reasoning power of man, as exemplified by the latter’s idea of a
suitable form of box for the artificial hatching of fish eggs. You will therefore
see why I asked, a short way back, whether eggs incubated in a rectangular
hatching box are properly oxygenated by the water in its upward progress
toward the outlet.

On this side of the Atlantic, wherever in the country districts there occur
diverging roads, a handing post to indicate the direction and distance of adja-
cent villages and towns is erected by the local authorities. Among our rural
folk, whose sense of humor is not of a wildly extravagant character, it is a
standing joke that their spiritual guides are like handing posts because they
point the way to all and sundry and never follow it themselves. But the pisci-
cultural writers of my acquaintance can not be held altogether free from some-
thing of the same reproach. To a man they impress on their readers the neces-
sity of extreme cleanliness as an absolute essential to success in pisciculture.
No one will be inclined to dispute the soundness of this advice until he attempts
to put it into application. Then he will be compelled, probably with some
reluctance, to confess he has attempted an impossible task. Leaving “extreme”
cleanliness out of the question, it will be found that even ordinary cleanliness
can not be observed, and for this reason: The rectangular hatching box is,
de facto, merely a pocket of water which can admit, but which, owing to the
position of the outlet, can not eject, extraneous matter that may enter it. It
therefore follows that when the alevins have arrived at the fry stage and require
feeding, any particles of food that they happen to miss must in the natural
order of things gravitate to the bottom of the box, where they become satu-
rated with water, decompose, and generate fungus. In this connection it must
not be forgotten that animal tissue, however carefully it is treated in converting
it into fish food, can never lose its identity as animal tissue. Its juices may be
dissipated and dried up by the application of heat and its substance by hard
pounding reduced to the finest powder, but its tendency to decompose is only
dormant and will actively assert itself immediately the powder or any portion
of it is brought under the influence of moisture. The filthy and insanitary
condition of the interior of a rectangular box after fry have been hand fed in
it for a few days can therefore be better imagined than described. My remarks
on this head are of course dictated by the assumption that the methods followed
by American and English pisciculturists are identical, viz, that the fry are

1020 BULLETIN OF THE BUREAU OF FISHERIES.

retained in the hatching boxes and fed until they are ready to be transferred
into the rearing ponds.

The shortcomings of the rectangular type of hatching and rearing box have,
I regret to say, occupied more space than I originally intended to devote to
them. Iam, however, assured that the interest and importance of the subject
to pisciculturists will be its own apology, if an apology be needed, for the tax I
have been compelled to impose on your patience and good nature before dealing
with the principles in construction which should be observed in making a hatching
and rearing box which will combine thorough efficiency with effective sanitation.
These are three in number and are as follows: (1) The material of which the
box is constructed must not only be impervious to water, but must have a
smooth, hard surface which will act as a preventive against the lodgment of the
spores of fungus; (2) the box must be shaped so that the water is kept in constant
circulation so long as the supply is running; (3) the outlet must be placed at a
point which will enable it to maintain a direct current over the eggs during their
period of incubation and at the same time, when the fry have to be fed, act
automatically to remove any small particles of unconsumed food.

As regards material, I have met with nothing equal to highly glazed earth-
enware, and were I in a position which would enable me to indulge in the luxury
of an experimental hatchery the whole of its equipment would be of china or
delft. These materials are, however, too fragile for the requirements of a
hatchery in which from 150,000 to 250,000 eggs are laid down each season, and
consequently we shall have to cast about for a material which will make an
effective substitute. Thin enameled iron, such as is used in the manufacture
of basins, pie dishes, and other domestic utensils, will answer the purpose
admirably. To me personally it is a matter of surprise that it has not already
been generally adopted for piscicultural work in preference to wood, seeing that
of the two materials it is, size for size, relatively the lighter. Moreover, it has
the additional advantage of being cheaper, is easier to keep clean, and possesses
far greater durability.

Coming to the second principle of construction, I have endeavored to show
that any approach to the conditions under which eggs are incubated in a natural
state is not attainable with a rectangular hatching box. It will, therefore, be
necessary to abolish straight lines in favor of curves, as indicated in the accom-
panying sketches. Perhaps, however, you may grasp my meaning more readilv
if, in imagination, you take a length of piping of fairly large dimensions and
divide it lengthways into equal halves. At each end of one of these halves
affix a circular head and you will then have an exact representation of the type
of box I am endeavoring to describe, but as yet minus the outlet. This consists
of a circular opening of at least 3 inches in diameter, cut at one end of the box,

AN IMPROVEMENT IN HATCHING AND REARING BOXES. 1021

its lower edge being exactly flush with the bottom of the box (fig. 1). The orifice
to which I refer opens into a pipe which is joined to it and runs upward to
within an inch of the top of the box, where it turns outward and acts as a spout
(fig. 2). The pipe must be of the same dimensions as the circular orifice. In
order to prevent the escape of alevins and fry, the orifice where the pipe is fixed
into the box should be covered with a grating of fine parallel wires at spaces
of about ;; inch apart. The grating maybe a little larger, but must on no
account be smaller, than the opening of the pipe on which it rests, or the ring to
which the wires are soldered will obstruct the passage of any light particles that
are being carried away by
the outfall. To support
the box two semicircularly
cut-out boards, placed on
edge, will be required
when it is placed in the ee
hatchery. These, I should Fic. 1.—Plan,
say, are detachable, the
box being held in position
by its own weight. Fig-
ure 1 will explain the ac-
tion of the box. It will
be seen that the supply
falls in at Band, so far as
the surface is concerned,
follows the course marked
by the arrows, while a cur-
rent extending from B toC
is caused by the outfall
picking up and ejecting
any light particles that
happen to gravitate withinits influence. It is needless for me to add that the
box must be fitted with a cover,so that the eggs may be protected from the
effects of the light during their period of incubation.

The furnishing of the box with baskets or with grills, as the case may be, is
a matter which must be left to the discretion of the pisciculturist who has to use
it. If baskets are decided upon they can be fixed in position exactly as they are
in the rectangular hatching box. If, on the other hand, grilles are employed, they
can be held in a light iron frame resting on a series of studs projecting from the
sides of the box. Next season I hope to have one of these boxes fitted with a
set of wire baskets, not more than an inch in height and divided by longitudinal
slips into compartments which will take five rows of eggs side by side. The

Fic. 3.—Cross section.
DESIGN OF PROPOSED HATCHING AND REARING BOX.

1022 BULLETIN OF THE BUREAU OF FISHERIES.

baskets will be shaped to the curve of the walls and will be in contact with the
bottom. By this means I think it will be possible for the eggs to receive the full
benefit of the current caused by the outlet.

The practice of feeding fry with artificial food while they are in the hatchery
appeals to me as being about as obsolete and out of date as the type of box in
which they are hatched. Not only does the preparation of the food and its sub-
sequent administration involve time and trouble, but there is attached to it the
danger of fungoid outbreaks from the particles which have escaped the notice
of the fry and are decomposing on the bottom of the box. It is within the
knowledge of every pisciculturist that fish raised from the same batch of eggs
and reared under artificial conditions always exhibit a considerable diversity of
growth; that is to say, there is an ascending scale of sizes running from what
may be described as ordinary fish to medium and large. In a natural state of
life, fry can and do feed whenever they are assailed by the pangs of hunger, but
in a hatchery they must perforce wait until the time fixed for the attendant to
come round and give them their food. My experience teaches me that the
divergence in growth to which I have referred is accentuated, if it is not increased,
by this intermittent feeding during the fry stage. For some time past I have
been using a curious little gregarious worm, the Tubzjex rrvulorum, which is more
generally known as the summer worm or mud worm, and I find that it makes a
magnificent food for fry from the moment they have absorbed the umbilical sac
until they are ready to go into the rearing pond. These little worms are found in
masses along the alluvial soil at the edges of ditches and ponds. They vary in
length from an inch to 3 inches and resemble in appearance animated threads
of floss silk. If the water above them is disturbed they will immediately dis-
appear by withdrawing themselves into their burrows in the soft mud. They
soon, however, recover from their fright, come out again, and at once recom-
mence the restless movements with which their numbers and bright color
attracted the passer-by. It is the tail end of the animal which is protruded out
of the mud. The skin of these worms is so fine and transparent that not only
can the blood be seen through it, but under an ordinary magnifying glass the
internal arrangements of the creatures may be plainly observed. When taken
from the water these worms resemble to the touch a piece of very soft jelly, but
their full beauty is not apparent until the lump is placed in a clear glass vessel
filled with water, when it assumes the appearance of a magnificent scarlet
zoophyte, with a multitude of waving tentacles constantly in motion.

In using these worms for feeding fry all that is necessary is to distribute
three or four pieces, about an ounce each in weight, at different parts of the
rearing box, and the fry will commence feeding upon them and will require no
further attention. Fry so reared make better blood and better bone than those
brought up on artificial food in the usual fashion, and, unlike the latter, they

AN IMPROVEMENT IN HATCHING AND REARING BOXES. 1023

never becometame. They also rise readily to floating particles, and consequently
I do not think that the slightest fear need be entertained that the use of these
worms as a primary food will train the fry to become ground feeders at a later
stage of their existence. TJ. rivulorum is pretty widely distributed throughout
England and the continent of Europe, but I have no idea whether it extends to
America. In regard to its introduction into the latter country, it is such a
fragile, insignificant creature that I do not think it could, under the influence
of an altered environment, do the slightest harm; and if any enterprising pisci-
culturist in the United States wishes to give it a trial I shall be very happy to
extend to him any assistance that lies in my power. Given a nice, soft stretch
of mud, covered by an inch or so of water, and an equitable climate, the mud
worm will flourish apace and multiply with a truly surprising rapidity. It has
been tried on trout fry in several of the leading hatcheries in England, and the
reports I have received concerning it have been of a most favorable character,
the only fault to be found with it being that it is an exceedingly expensive food.
As the hatcheries mentioned above have had to purchase their supplies from
London at the rate of 3 shillings 6 pence per quart, this complaint is quite
justified, but if the pisciculturists who make it will only go to the small amount
of trouble necessary for laying out a worm bed, they will find that T. rivulorum
is a cheap and invaluable food for their fry.

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