—Lancaster Farming, Saturday, December 18, 1971
6
Delaware Study Shows Good Potential
Editor's Note. We're sure most of our readers know what
catfish are. Catfish abound in the Susquehanna River and in
local streams. Many fishermen find them to be good sport. But
did you know that catfish are a very profitable crop in many
states, particularly in many of the Southern states? Many
items cross our desk on the subject. This one proposes catfish
production a little closer home. While we doubt if our readers
are interested in growing the finny crop, we think they’ll enjoy
reading about how it’s done.
Delaware’s newest crop needs
lots of water
It takes water to grow catfish
plus quite a bit of know-how
But grain-fed channel cats can
be a profitable crop with a ready
made market, according to
Kenneth Lomax, University of
Delaware assistant professor of
agricultural engineering
His small-scale retail sales test
showed that an enthusiastic
market does exist Consumers
wrote him, “It’s better than
trout” “mild” “no fishy
taste ”
As one old-timer put it, “This
fish compares to channel cats I
caught off Bowers Beach in the
1930’s ”
The test catfish sold for $1 a
pound Lomax says this price
would allow for a profit of four to
six cents per pound for the far
mer—slightly more if he cleans
and dresses the fish himself
Farmers who already have a
pond can grow catfish in a cage in
the pond either for sport or as a
source of a little extra income, he
says Before putting m a pond,
however, check the sod type
Clay holds water best
However, tank-raising offers
several advantages to growers
who want a more substantial
profit
Catfish can grow all year round
Tank-raised catfish reach eating size in 10-12 months.
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Catfish—A New Farm Crop?
in tanks because temperatures
can be controlled Lower pond
temperatures during Delaware
winters don’t kill the fish, they
merely stop growing or lose
weight In a tank, it takes 10
months for a catfish to grow to
eating size from a fingerhng—l2
months from eggs
A search for inexpensive
temperature control methods led
Lomax to his work with “catfish
under glass ” He put a plastic
greenhouse structure over the
tanks Two layers of plastic are
inflated over steel ribs, similar
greenhouses are used for growing
plants “This keeps the fish
cooler in summer and warm
enough in winter ’’
An adequate oxygen supply is a
vital factor in tank fish farms,
although it’s rarely critical in
ponds unless they’re too heavily
stocked In Lomax’s research, an
electric pump cycles water
through a filter and bubbles it
back into the tank The bubbling
supplies oxygen
A standby generator and an
alarm system that signals
electric breakdowns are needed
Tanks should be without pumps
for no more than two hours
Lomax has designed an
ingenious filter system that
removes waste products so ef
ficiently that tank water doesn’t
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This ingenious filter system recycles
water from catfish tanks so efficiently that
they can thrive in the same water for 10
months. Kenneth Lomax, University of
“Catfish under glass,” a new system of raising catfish in
large tanks under a plastic greenhouse, has been
developed at the University of Delaware. Catfish will grow
at any time of the year, despite Delaware winters.
need to be changed at all during
the 10 months the fish are
growing The small filter tank
sits above the large growing
tanks
Three layers of gravel m the
filter act as a mechanical sieve to
remove uneaten food and other
solid wastes
Bacteria on the gravel break
down the liquid fish wastes to the
point where they can be used by
plants For instance, Lomax has
duckweed and waterspnte, two
water plants, growing in the filter
tanks. Watersprite could even be
sold as an aquarium plant and
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ALLEN H. MATZ, Inc.
505 E. Main St., New Holland
Delaware assistant professor of
agricultural engineering, grows sea plants,
fertilized with fish waste, which can be
dried and fed back to the fish.
duckweed might be dried and
used as fish food.
“That’s really recycling,”
Lomax laughs. “From fish to
plant to fish food ”
His tanks are concrete, set in
the ground and hold 4,000 gallons
of water each. However, for farm
systems he recommends wooden
tanks holding 1,000 gallons each.
Each tank, with the necessary
pump and filter, would cost
approximately $2OO. About one
fish per gallon could be stocked.
One man could care for as
many as 52 tanks by himself even
without a fully automated
system. And, 52 tanks could
produce 1,000 pounds of catfish
each week —year round.
(Continued on Page 7)
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