Introduction
For the past two decades, aquaculture has been
the fastest growing sector in agriculture. Common
in many supermarkets today are fresh
channel catfish, produced mainly by fish farms
in the South, and trout from the Northwest.
Recent emphasis on agricultural diversification
has led many Iowans to consider fish as a
potential crop.
Current Status
The number of private fish hatchery licenses
issued in Iowa has doubled within the past 10
years. In 1988, the Iowa Department of Natural
Resources issued 69 commercial permits to 62
Iowans and seven out-of-state fish producers.
Most are located in eastern and southeastern
Iowa where the soil and topography lends itself to
the construction of farm ponds. Notable exceptions
are several trout hatcheries, which need a
constant supply of cold water from springs or
wells, in central and northeast Iowa.
A survey of Iowa aquaculturists found that most
operations produce fish for stocking purposes.
However, many fish were reared for human
consumption, and some operators generate
income from ponds where members of the public
pay to fish. Channel catfish were the most commonly
reared fish for stocking and direct food
use. Largemouth bass and bluegill were second
in importance, sold exclusively for stocking
purposes.
Other species common to Iowas aquaculture
business, in decreasing order of importance,
were walleye, grass carp, fathead minnows,
crappie, trout, smallmouth bass, northern pike,
buffalo, wipers, and crayfish. Wipers is a
common name given to a hybrid bass produced
by breeding a white bass female with a striped
bass male. Many producers in eastern and
southern states consider farm-reared wipers
comparable to striped bass, whose dwindling
numbers along the Atlantic coast and Gulf of
Mexico resulted in a ban on their commercial
harvest several years ago.
About one-fourth of the Iowa aquaculturists
surveyed indicated they were new to fish farming.
Most seemed optimistic about the future of their
operation but found the work to be more difficult
than they had anticipated. In response to increased
interest in aquaculture, several regional
junior colleges and universities offer vocational or
supplemental adult classes in fish farming.
Production Considerations
The widely accepted idea that Fish + Water + Food = Money is a misconception. Sound planning and collection of available information can help a prospective fish farmer decide whether or not to pursue this venture, and it can prevent expensive mistakes. Important factors to consider before pursuing a fish production are:
- water,
- rearing facilities,
- species to produce,
- feeds and feeders,
- disease and treatment,
- harvesting, and
- marketing.
The following comments are not meant to encourage or discourage fish farming, but to provide factors on which to base a sound decision.
Water
The most serious threat to profitable fish production
is poor water quality and lack of an acceptable
quantity of water. Without adequate quantities
of good quality water, fish production may be
costly or impossible.
Three basic sources provide water for fishing
operations: 1) wells, 2) springs, and 3) surface
runoff. The preferred source is a deep well or
spring; however, the most common source for
most operations is the use of surface runoff.
Surface water makes fish rearing difficult because
the source often is polluted and contains
wild fish populations with associated diseases.
Water from wells and springs is free of unwanted
fish; however, both sources may be low in oxygen
and require aeration. Well water also may be
high in iron, carbon dioxide, or nitrogen gas, all
of which can be toxic to fish, and must be removed
before use. See table 1 for a description of
those factors that affect water quality.
Portable test kits and meters can identify water
quality parameters. For initial testing of important
water parameters, several laboratories are
available on a fee basis.
Water quantity is as important as water quality.
For a pond culture, approximately 13 gallons/
minute/pond surface acre should be available for
flushing or refilling a pond. Several inches of
water can evaporate from a pond during one
year. Runoff water supplies make ponds difficult
to manage because water may not be available
when needed, such as in midsummer, or too
much water may flush fish from the pond. For a
raceway culture, enough water should be available
to completely change the water in a raceway
one to two times per hour.
Rearing facilities
Ponds: Many first-time fish farmers have an existing pond in which they would like to grow fish. This can work well, but a few guidelines must be followed:
- The pond bottom and water should be analyzed for pesticide contamination.
- The pond should be at least 8 feet deep to protect fish from summer drought and winterkill.
- The bottom should be uniform and free of stumps to simplify harvest.
- The pond should possess a screened outlet to prevent fish from escaping.
- The pond should be free of all unwanted fish.
If a pond is constructed for personal use only, no other special features are needed. For commercial use, the following pond features are recommended:
- The soil should be at least 20 percent clay below pond bottom.
- The pond should be drainable within 7 to 10 days.
- The facility may have a concrete harvest basin with water supply.
- The area must be accessible to vehicles.
- The pond must be at least 4 feet deep in the shallow end and 10 feet deep at the harvest end.
- The facility must have an overflow if it is built on a substantial floodplain.
Cages: Small wire enclosures, about 4' x 4' x 8',
float in existing ponds and are anchored to the
shore or a dock by rope or cable. Fish reared in
cages are easy to observe, feed, and harvest;
however, disease treatment is difficult without
removing the fish from the cage or treating the
whole pond.
Raceways: Raceways are used by commercial
producers interested in the intensive (concentrated)
culture of fish, such as the rainbow trout
and channel catfish. Water usually is obtained
from a spring or stream and is passed through
the raceway using gravity, a once-through or
open system. Raceways are arranged in a series
on slightly sloping terrain, thus taking advantage
of gravity to move the water through each unit.
Raceway dimensions vary, but generally a
length:width:depth ratio of 30:3:1 provides
favorable characteristics. Most raceways are 3 to
6 feet wide and 20 to 100 feet long, but they also
can be circular.
Raceway construction or purchase can be expensive
and a large supply of good quality water is
required. Raceways are constructed of concrete,
block, tile, bricks, wood, or other durable materials,
or they can be earthen. Earthen raceways
may be less expensive to construct than other
types; however, the high volume of fast-moving
water cause varying degrees of erosion. Thus,
raceways are not often used. They often require
daily cleaning to maintain a good environment.
| Table 1. Factors that affect water quality. | ||
| Water parameter (when to check) | Recommended levels | Importance |
| Oxygen (daily) | Minimum: 4-5 ppm Maximum: not to exceed 150% saturation for 4-6 hours |
Main cause of fish stress and death during high production |
| pH (daily) | Minimum: 6.5 Maximum: 8.5 |
Fish do not grow well outside these ranges; a good indicator of water quality. |
| Alkalinity/Total hardness (weekly) | Minimum: 20 ppm Maximum: 400 ppm |
Acts as buffer against water pH changes, affects behavior of chemicals in water and fish survival. |
| Iron (annually) | Maximum: 0.5 ppm or below | Kills young fish by suffocation, commonly found in wells and springs. |
| Ammonia (weekly) | Maximum: 0.012 ppm (trout) 0.12 ppm (catfish) |
Excess causes gill damage, reduced growth, and death; toxicity affected by pH. |
| Temperature Range | Trout: 45F-60F Catfish: 65F-85F |
Outside these ranges reduced growth occurs and extremes may cause stress. |
Production in raceways is greater than that of
ponds or cages as a result of the continual
exchange of freshwater, which removes the
wastes. Production is based, in part, on the
amount of water flowing through the raceways,
yields are measured in pounds per gallon per
minute (lb./gal./min.). Yields exceeding 82 lb./
gal./min. have been obtained in very intensive
raceway production.
Water reuse systems: A closed reuse system
recirculates water rather than passing it through
the system only once. Less water is needed for
this system than for ponds or open raceways.
Most reuse systems are located indoors, which
allows the grower to maintain control over the
water, such as temperature. Reuse systems have
additional advantages; however, their major
disadvantage is the start-up cost.
Closed reuse systems have four parts: the culture
chambers, a primary settling chamber, a
biological filter, and a final clarifier or secondary
settling chamber. Each unit is important to the
system, although some closed systems do not
contain all four components. Components may
be separate units or they may be arranged in
combinations that make the system appear to
have only one or two units. Components may be
large or relatively small, but each must be in
proper proportion to one another if the system is
to perform properly.
Production rates in closed reuse systems vary
considerably depending upon the type of system
and the users expertise. Yields can range from
0.25 to 0.8 pounds per gallon (lb./gal.), although
these figures can be misleading. Large-scale
reuse systems are not recomended for persons
with little experience in aquaculture.
Species to produce
Many species are produced commercially in Iowa;
however, channel catfish, rainbow trout, large
mouth bass, and bait fish are most common.
The choice remains with the fish farmer, although
available rearing facilities, potential
market, water supply, and water temperature
should influence the decision. Catfish, bait fish,
and bass prefer 70F to 85F water temperatures
while trout do best in 45F to 65F water. The
most important factor to remember is that the
growing time from egg to finished food product
will be at least two years in Iowa. Bait fish and
small stocking fish require less time and effort
to produce, however, competition in this
market is intense both from in-state and
out-of-state producers.
Feeds and feeding
The fish farmer must have a knowledge of fish
nutrition and be able to manipulate natural
foods (plankton) along with formulated dry diets.
Good commercial feeds are available for a variety
of fish, and for particular species, such as channel
catfish, trout, and salmon. The fish farmer
must know how water temperature, water quality,
feed quality, feed size, and feeding frequency
affect eating habits, especially if feeding species
other than channel catfish, trout, and salmon.
A good aquaculture program requires fish be fed
3 to 5 percent of their body weight 6 to 7 days
per week, and at the same time and place in the
pond or raceway. With good management practices,
a pond can produce 1,500 to 2,000 pounds
of channel catfish per acre of water.
Disease and treatment
The aquatic environment contains a variety of
disease organisms and, thus, potential for disease
problems. Disease can be caused by anything
that produces stress; such as low dissolved
oxygen and other water quality problems, handling,
poor feed or feeding practices, drastic
temperature fluctuations, and crowding. Bacterial
and parasites are the most common diseasecausing
organisms, which can result in the death
of many fish. However, fish usually will give the
attentive fish farmer advance signs of a potential
problems. Common indicators of fish stress and
disease include reduced feeding activity, lazy
swimming, and the appearance of dead fish.
The best control for disease is prevention. This is
accomplished through proper management,
maintenance of good water quality, and insistence
that the newly acquired fish be free of
stress and disease.
Even with these precautions, disease may occur
and chemical treatment may be necessary.
Before selecting a chemical, the culturist must
identify the disease and know how the chemical,
water, fish and disease will respond to the treatment.
Chemical treatments can be expensive, are
no panacea, and may cause higher mortality
than the disease outbreak. Experience indicates
disease problems and fish loss will continue to
reoccur until the stress factor (crowding, poor
water quality, handling, etc.), which precedes a
disease outbreak, has been identified and removed.
The fish farmer must know which chemicals
are legal to use and their correct application.
Harvest
Harvest is an important aspect of fish farming
and is often given low priority. Any damage to
salable fish during harvest or transport can lead
to a lower fish value, or fish death, and a complete
loss. Harvesting techniques are similar for
all species; however, scaled fish (walleye, bait
fish, bass) are more prone to injury and require
careful handling.
The time of harvest can be affected by market
availability, the size of the fish needed, and
weather. In general, fish handled in cool water
are stressed less than those handled in warm
water. Fish also should not be fed 24 to 36 hours
prior to harvest to reduce fish stress and fouling
of hauling tanks. Harvest during hot weather can
cause off flavor, oxygen depletions, fish loss,
and generally poor quality fish. Common equipment
needed include seines, holding facilities,
graders, dip nets, scales, boats, hauling units,
aeration equipment, tractors, and trailers.
Marketing
This last section should be first in the minds of
all potential fish farmers. Before fish rearing
facilities are built or fish are stocked in existing
ponds, a fish farmer must know where to sell the
product.
The three types of fish commonly producedfood
fish, small fish for stocking, and bait fishappeal
to different markets. Food fish are sold to area
consumers and must be processed, either at a
central plant, which are limited in Iowa, or at the
farm. These fish also are sold live wholesale or
retail to local customers or haulers. Food fish
can be sold to lake owners as catchable fish or
harvested from the production pond by anglers
for a fishing fee. Fish raised for stocking fish or
bait can be sold to local pond owners and
anglers, but often transportation of these fish
over a large area is necessary.
A final consideration is when to sell. Due to
similar growing seasons, many producers sell
fish at the same time. This can create an oversupply
and lower prices. Fish farmers can be
flexibile by adjusting stocking dates or fingerling
size at stocking, partial harvesting, or harvesting
during an off-season.
Fish farming is similar to the production of other
livestock. A successful operation requires technical
expertise. If youre considering fish farming,
look at all points discussed above, then discuss
your situation with an experienced fish producer.
This should help ensure a satisfying and profitable
investment in fish.
Legal Considerations
The Department of Natural Resources and the
Department of Inspection and Appeals should be
contacted as soon as possible to determine
permits needed for an aquaculture operation.
The following laws and regulations are summarized
for convenience. In addition to these laws,
local zoning, health, and other regulations may
apply.
These licenses are available from the Department
of Natural Resources: 900 East Grand, Des
Moines, Iowa 50319.
Aquaculture unit license: Needed to operate a
hatchery, to engage in the business of propagating
fish in private waters, or to hold fish for
commercial purposes. The state conservation
officer in your area must approve the application
before a license can be issued. The licensee is
allowed to possess, propagate, buy, sell, deal in,
and transport fish produced from breeding stock
lawfully acquired.
Operators must secure breeding stock from
licensed private fish hatcheries in Iowa or from
lawful sources outside the state. The Department
of Natural Resources can provide a list of licensed
Iowa fish hatcheries and a list of conservation
officers for each county.
When purchasing fish, keep the bill of sale that
allows possession to spawn, rear, and harvest
fish. Additionally, anyone bringing fish or fish
eggs into Iowa that are not native must submit
an application to the DNR and receive a permit
prior to transporting the fish into the state. The
DNR may require certification that the source of
fish or fish eggs is disease-free.
Bait dealers license: This license is required if
minnows, frogs, or clams are sold for fish bait.
The license also allows the licensee to obtain bait
from lakes and streams where permitted.
NPDES permit: This permit, from the National
Pollutant Discharge Elimination System
(NPDES), is needed for discharge of used water.
Generally, only relatively large operations or flowthrough
hatcheries will need an NPDES permit.
Water withdrawal permit: This permit is required
if withdrawal from a groundwater or
surface water source is in excess of 25,000
gallons per day.
Water storage permit: The permit is needed if
natural runoff is captured and stored (e.g., a dam
across a waterway) and the permanent storage is
in excess of 18 acre feet.
Well construction permit: This permit is required
prior to construction of new water wells.
Floodplain development permit: This permit
may be needed if a fish farm is constructed on
the flood plain of a stream or if a dam is constructed
across a waterway or stream.
The Department of Inspection and Appeals
requires a permit to operate a processing plant or
slaughterhouse where fish are killed or dressed
for food. Persons planning to raise fish for food
should contact: Department of Inspection and
Appeals, Lucas State Office Building, Des
Moines, Iowa 50319.
Bibliography
Depree, H.K., and J.V. Huner. 1984. Third report
to the fish farmer. U.S. Dept. of Interior,
U.S. Fish and Wildlife Service.
Grizzell, R.A., O. Dillon, Jr., and E. Sullivan.
Catfish farming: A new crop, Bulletin No.
2244, U.S. Dept. of Agriculture.
Jensen, J. Channel catfish production in ponds,
Circular ANR-195, Alabama Cooperative
Extension Service. Auburn University.
Piper R. et al. 1982. Fish hatchery management.
U.S. Dept. of Interior, U.S. Fish and Wildlife
Service.
Wellborn, T. Production of channel catfish. Publication
622. Mississippi Cooperative Extension
Service, Mississippi State University.
Wellborn, T. Guide for prospective catfish
farmers, Publication 1465. Mississippi
Cooperative Extension Service, Mississippi
State University.
Source: Iowa State University - August 1992
