An Introduction To Aquaculture

by William O. Mctarney, Ph.D.

The best argument for aquaculture is based on the ever-increasing need for protein foods. Fish and aquatic invertebrates are efficient food i converters, capable ot producing more protein ) per unit area from the same amount of food than their warm-blooded counterparts. The quality of protein is the highest available from animals and is the lowest in fat content.

The farm pond is usually stocked with large-mouth bass and bluegills, and is designed to provide sport fishing with food as a fringe benefit. Even when managed with recreation in mind, the farm pond has been shown to produce a substantial amount of edible fish and, it is my belief that, properly managed, it could become a really significant factor in the nourishment of many families.

More than a few American farmers have made the logical transition from eating pond fish to fish cidture for the express purpose of food production, often on a commercial scale. They are usually encouraged to go into farming rainbow trout or channel catfish. The former species has produced fantastic yields but requires a large and dependable supply of water at a constant temperature—a condition which can be met by only a few landowners. Catfish farming is more amenable to most farmers as it tan profitably be carried out in warm, still water.

Almost all trout farmers use antibiotics, not only in disease treatment, but as a prophylactic measure in their stock's diet. Use of antibiotic feeds is increasing in catfish culture, and many farmers also apply chlorinated hydrocarbon herbicides as a matter of course. Researchers at the New Alchemy Institute in Falmouth, Massachusetts, and at Rodale Resources Incorporated in Emmaus, Pennsylvania, are seeking alternatives, however.

Trout and catfish farming in the United States is further characterized by monoculture and heavy feeding. The latter will almost always increase production and may be necessary in large-scale commercial fish culture, but it certainly is not necessary to produce yields appro-l priate for personal, family, or community use. Asian fish culturists produce thousands of pouifds of food fish which derive their nutrients essentially through organic pond fertilization or enrichment from surrounding farmland, through cut grass, vegetable tops, or other such inexpensive feeds. Similar systems are beginning to evolve in Africa, where considerable success has been achieved with community fish ponds stocked chiefly with herbivorous tilapia.

The direct or indirect utilization of organic wastes by fishes is by no means the only way in which fish ponds can contribute to the recycling capacity of a farm's ecosystem. Excess fish or fish too small for human consumption may be com posted or fed to other livestock such as hogs or chickens. Under certain conditions, metabolic wastes from fish and shellfish may be applied beneficially to vegetable crops without harvesting the fish.

Pol yen It me is a widely applicable technique, with high yields being its most obvious benefit. The Chiiie«« employ a highly refined pofycultttre technique v.hiih supplies them with a substantial supply of fish as it recycles their waste products and fertilizes their gardens. They build their latrines and animal shelters with slatted floors over the pond for organic wastes to fall through and supply the pond with a nutrient source. The pond becomes rich with algae feeding on the manure and provides a foundation for a complicated food chain to build upon. Algae- and manure-rich water is syphoned off to irrigate the garden and fertilize it at the same time.

A further benefit of polyculture includes providing the farmer with greater economic stability. (If one crop tails; there's always some-tiling else.) It also reduces the likelihood of a disease or pest destroying the entire crop, with the consequent temptation to use chemical poisons.

It would seem, then, that American food growers at all levels of the economy should not only consider taking up aquae allure, but should also be busy developing modern American analogs of the traditional Oriental pond polvruhurc systems. When integrated with similar practices on the land, such systems have the potential to revolutionize American agriculture—organically.

WATER QUALITY

When employing intensive fish culture techniques, it is advisable to monitor the water quality. A thermouieler is a must for all pontl owners, but the intensive aqiiaculfurist must also worry about dissolved t>xyj»en and ammonia content in water, Too much ammonia or too little

Frequent letting of water quality for excesses of ammonia or any oxygen deficiency will warn the fish farmer of problems before they become critical.

oxygen quite often will result in fish kills. And with intensive fish culture, small deficiencies or excesses can rapidly reach dangerous proportions.

There are several companies which manufacture chemical testing kits for under $50, and one company manufactures a meter for measuring dissolved oxygen for a hit over §100.

Several companies manufacture water test equipment, but it is generally designed for precise research work, so prices tend to be bigh. For example, laboratory-quality oxygen meters, accurate to tenths of a part per million, start at $500. However, the Garcia is designed for fishermen, is less accurate but accurate enough, and costs a little over $100 (1977 price).

The other option for farm pond water testing is to use chemical kits. They require more time, to mix solutions and add chemicals to water samples, but they are much less expensive. The chemicals are pre measured in little packets called pillows to make die procedure as expedient and simple as possible. Chemical test kits are available to measure dissolved oxygen, pH, nitrogen ammonia, hardness, C0a, and many other factors.

Garcia D.O. Meter

The Dissolved Oxygen meter is available from: Garcia Dissolved Oxygen Meter 329 Alfred Ave. Teaneck, NJ 07666

Tett Kit»

Chemical test kits are available from: La Motte Chemical Products Co. P.O. Box 329 Chestertown, MD 21620

Hach Chemical Co. P.O. Box 389 Loveland, CO 80537

AERATION

Most fish deaths occur because of an oxygen deficiency. Excessive alg.<e and weed growth may rob ponds of oxygen, and the ammonia produced by fish waste products seriously affects water quality. Decomposing plant and animal ma terials may also contribute to oxygen loss and ammonia buildup. Aeration equipment offers relief from oxygen deficiency and excess ammonia problems.

Aerators can be divided into two main categories, mechanical aerators and agitators which transfer atmospheric oxygen into water, and diffusers, which are tubes that introduce oxygen bubbles into the water under its surface. Anyone who has seen an aquarium filter in operation knows fiow this type of aerator works.

Floating mechanical aerators use a pump to spray sheets of water above the pond's surface. This spraying action causes the water to absorb oxygen, aids in the removal of carbon dioxide and ammonia, and also may slightly lower water temperatures. Agitators are usually equipped with paddles which stir the water, causing it to oxygenate at the surface.

These positive features are clouded by a few disadvantages as well. Floating aerators and agitators should not be in operation while anyone is boating or fishing because they present an electrical hazard. They also obstruct the natural look of the pond. Some companies have manufactured aerators with decorative spray patterns in an effort to turn this negative feature into an attribute.

Diffuseis, on the other hand, oxygenate the water while submerged, so they don't interrupt the aesthetics of the landscape or prohibit swimming or boating. Because of the equipment necessary for installation, such as air compressors and air pumps, di if users are generally a more-expensive enterprise. Operation costs are generally higher because of a higher power requirement.

SOURCES OF AERATORS

Air-o-Lator

A floating mechanical aerator, the Model AF-14 has a totally submersible i/s h.p. (115 volts, 7 amps under full load), stainless steel, electric motor which moves 350 gallons of water per minute, and comes with a 50-foot cord. Shipping weight: 35 pounds.

Air-o-Lator (Div. of Roycraft Industries)

8100 Paseo St.

Kansas City, MO 64131

A cross section of the Airo-l.ator illustrates the position of the pump and impeller within the supportive float of a mechanical aerator. Airnljioi

Aquacharger

This unit isa ceramic difhtser-aeraior. The manufacturer states ti tit t a single unit is sufficient to aerate a I- to 2-atre lake 10 to 25 feet deep. The diffusing cylinder is 2.25 inches in diameter and 9.5 inches long. It will circulate water to a radius of 20 to 30 feet at the pond surface. Additional equipment needed for operation are a buried electric line with an outlet socket, ¡i waterproof pump house on a concrete slab, an air pump, and copper tubing. Overall life of the unit is estimated at 10 years.

Environmental Management & Design, Inc.

Ann Arbor, Ml 18107

Ar/ua/harger Ceramic Diffus,7r-Aerator Environmental Management fe Design, Int.

Aqua Puss

The Aqua Puss is an air diffuser-aerator. Air is released from the diffuser in sufficient volume to maintain turbulent uplift at a rate at which oxygen transfer can take place. The water jet propels water enough to carry it above the water surface, making a rise in the pond. The water then (lows back upon itself and is converted to a horizontal flow 360 degrees 3round the rising column.

Schramm, Inc. 901 E. Virginia West Chester, PA 19380

Hoatcyclc Company

They are agitation equipment manufacturers. The Big Bull agitator has a 110-voli, t/jj h.p. motor with a one-year warranty against defective materials and workmanship, provided all repairs have been done by the manufacturer.

Boatcycle Co. P.O. Box 494 Henderson, TX 75652

Crescent Agitators

Crescent manufactures agitators in a variety of sizes for everything from small hauling and holding tanks to outdoor ponds. Bdh indoor and outdoor models are available.

Crescent Mfg. Co. P.O. Box 3303 | Fort Worth, TX 76105

Air distribution system of a diffusing aerator.

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Air jet Aerator

The makers of the Air Jet manufacture various kinds of agitation equipment. In this aerator, air is drawn down through a tube to a propeller and broken up into tiny bubbles. The water level will not alter the effectiveness of the unit. Models for both transport and pond aeration are powered by 110-volt, y3 h,p., fan-cooled, continuous-duty ball bearing motors.

Commerce Welding & Mfg. Co., Inc. 2200 Evanston St. Dallas, TX 75208

Fresh-Flo

In this centrifugal action aerator, a propeller-impeller draws water into the unit and initiates a tremendous force. Water is passed through slots above the water line, and sheets of water are sandwiched with open air. This aerator is mounted on pipes, floats, or overhead installations and provides a continuous circulation process.

Fresh-Flo Corp. Rt. 1

Adell, WI 53001

GenAIRator

This diffuser-aerator will aerate and circulate 6,000 gallons of water per hour (100 gallons per minute), and add £0 pounds of oxygen to the water per day. The \/A h.p. motor has a thermo protector which shuts tlK motor off temporarily during periods of low voltage or current shortages. There is no float, standpipe, or overhead support; it needs no adjustment to different lake levels. This model poses no hazard to boaters or swimmers, and it has a one-year guarantee.

53092

McDonald Oxidator

Unlike many hanging aerators, water level is not critical with this agitating oxidator. It operates effectively when immersed in 3 to 12 inches of water. Aeration occurs at the surface by an agitating blade and at the bottom of the oxidator by an air rotor. The unit is engineered to aerate more with less agitation.

McDonald Bait Co. Rt. 2, Box 300 Erin, I N 37001

Micro-por

This air difluser-aerator consists of ABS thermoplastic tubing containing approximately 1,000 microscopic holes per linear foot. As air is introduced through the tubing at low pressure, it seeps out through these tiny pores along the entire length of the Micro-por pipe. Available in 100-foot coils or in 5-foot straight lengths with i/o inch male thread adapters.

P.J. Minneau

Floating and submersible aerators are available from this company in the following sizes:

1. A 5 inch unit with a i/3 h.p. electric motor which aerates 100 gallons per minute at ]/2 cent per hour;

2. A 5 ilicit unit with a y<> h.p, electric motor which aerates 200 gallons per minute at I cent per hour;

A f> inch unit with a I h.p. clecuic motor which aerates 400 gallons per minute at 2 cents per hour; and 1. A 5 inch unit with a '¿y» h.p. gasoline motor which aerates 500 gallons per minute at 10 cents per hour.

A I i/u inch pipe is needed for installation, its length depending upon the water depth and the depth it must be driven into the bottom to be firmly situated (submersible type). (Electrical costs were calculated in 1977).

P.J. Minneau Machine Co. Lime Kiln Rd., Rt. 6 Green Bay, WI 51301

Floating mechanical aerators, like thit Otterbine Mechanical Aerator, may need io be held in place by mooring cables.

Otterbine® Aeration Systems

These compact 1, 2, 3 and 5 horsepower Moating mechanical aerators are designed to improve water quality in fish ponds by increasing the supply of dissolved oxygen available to the fish and by mixing the water to distribute dissolved oxygen to various depths.

With aeration, fish can be stocked more heavily, reach eating size faster, and are less vulnerable to diseases and parasites.

Otterbine aerators are installed by floating them into position in the pond, and mooring or anchoring them in place. An underwater power cable leads to on-shore electrical service. The 1 and 2 horsepower models require either 115 or 230 volt single-phase power; the 3 and 5 horsepower models require 230 or 460 volt three-phase power.

Alt Otterbine aerators are warranted conditionally against detects in materials and labor for one full year from date of delivery.

Rodale Resources Inc.

576 North St.

Eir aus, PA 18049

Vulcan Aerator Company

Vulcan's model No. 12 has a 12-volt, ball bearing, totally enclosed motor, with continuous-duty, replaceable brushes. Domes are available for splash-free operation, and it requires 31/2 amps at half-paddle, Model No. 10 has a 1.5-amp, alternating current motor which operates at a slower speed,

Vulcan Aerator Co.

Germantown, WI 53022

Xodar Corporation

Xodar's Model 360 is a submersed aeration diffuser. The air flow volume is very low in order to achieve sufficient discharge pressure to produce an effective bubble swarm for the desired maximum oxygen-to-water transfer.

Xodar Corp. Powder Hill Dr. Lincoln, RI 02865

FEEDING

Two conditions encourage the use of supplemental feeding of farm pond fish: when the stocking density is higher than what would occur naturally and thus exceeds the natural food supply, and when an increased growth rate is desired. High-protein, pelleted commercial feeds satisfy both conditions and are available at most local feed stores.

Feed pellets are in either floating or sinking form. Floating pellets permit the farmer to watch his fish feeding. He can check growth as well as gauge what amount to feed. The activity with which fish feed is indicative of their health; heaUhy fish feed actively.

Sinking pellets insure that smaller, more timid fish are fed also. Every fish will eat, not only the big, aggressive fish cruising the water surface. Often pond owners use a combination of floating and sinking feed to reap the benefits of both. Feeding habits are species-specific. Thus, fish farmers should select feed according to recommendations for the variety they are raising.

Fish feeds come with different protein ratios; selection depends upon how extensive the feeding program is. If commercial feed is used only to supplement the fishes' natural diet, a tower protein rado (25 to 30 percent) is used. If it is the major portion of the diet, then a higher protein ratio (30 to 40 percent) is recommended.

Many pond owners feed their fish by hand. This method is economical, but requires that the owner always be present at feeding time. Purchasing an automatic commercial feeder can easily involve an investment of $100 or more. The simplest feeder is a floating ring which merely confines food to one spot rather than having it float all over the pond. A design carrying the floating ring idea one step further is described in the following build-it-yourself plan. If you have decided to feed by hand, this feeder can make the venture easier while Utilizing ft¿d more effectively.

BUILD-IT-YOURSELF FEEDER

This feeder can be used with both sinking and floating feeds. While sinking pellets drop into a sloped screen tray, floating feed remains

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