Fish Farm with Cages!

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WHY USE CAGE CULTURE?

The outstanding advantage of cage culture is that it permits "fish gardening" in bodies of water that aren't suitable for more intensive aquaculture (in which large nets are used to harvest the crop). Such locations include the following:

Public (or large private) waters: Harvesting of fish from public waters is usually restricted to sporting, single-line methods ... while privately controlled ponds that cover more than an acre can present formidable difficulties to aquaculturists hoping to harvest with nets. Yet such environments are often ideal for cage culture.

Multipurpose ponds: Maybe your pond was built to attract wildlife ... to offer recreational fishing and swimming ... or just to provide scenic beauty. Converting that entire body of water to intensive fish culture may be difficult, and doing so would certainly compromise—or even render impossible—some of its other uses. However, you could easily produce several hundred pounds of cage-cultured protein without lessening your ability to enjoy the pond in many other ways. (Cages may even attract wild fish, and thereby enhance sport fishing!)

Ponds with more than one owner: Suppose your land fronts on a private body of water that's shared by a number of households. Since each family probably has its own ideas about how best to enjoy the pond or lake, you might have a good bit of difficulty getting all of the owners to agree on a joint aquaculture management plan. But you could keep a few cages floating off your own shoreline without interfering with your neighbors' chosen activities.

Very deep ponds: Deep bodies of water—such as quarry pits—usually are not productive as conventional aquaculture sites. 'But the same sites are often good for cage culture.

Brushy ponds: Some ponds are so full of brush, logs, or other obstacles that net-harvesting is all but impossible. But as long as—there are patches of open water, such locations can be used for farming.

(Incidentally, the fish containers can also be used in the sea and, on occasion, in rivers and streams. But in this article I'll deal solely with standing bodies of fresh water.)

KINDS OF FISH

Although most fishes probably can be raised in cages, experience to date suggests that, if you're more interested in production than experimentation, you should select from the seven varieties listed below:

Channel catfish (Ictalurus punctatus): This is the fish most often raised commercially in the United States. Consequently, abundant technical information and good stock are readily available. Channel cats make for excellent eating, too, but they are somewhat costly to feed and relatively susceptible to disease.

Bullheads: In my opinion, bullheads are among the tastiest of all the North American freshwater fishes. What's more—based on our experiences at the New Alchemy Institute—they seem to be some of the most suitable for home cage culture. In order to be successful, you'll need to know exactly which species you have. At New Alchemy, we had great success with yellow bullheads (Ictalurus natalis), but we had miserable luck with our sole attempt at raising brown bullheads (Ictalurus nebulosus). Some 90% of the caged browns died within a few weeks of stocking, even though the same species did fine if allowed to swim freely in the same pond! (We never tried rearing any other species.)

The three most widely distributed bullheads—yellow, brown, and black—appear quite similar ... and despite their names, you can't distinguish them by color alone. Your nearest state or provincial fishery biologist (or a good field book) should be able to help you learn the distinguishing characteristics, however. [EDITOR'S NOTE: This issue's center spread might also prove helpful.]

Trout: The ever-popular rainbow trout (Salmo gairdneri) is the "number two" species in North American commercial fish culture. Like channel cats, trout are easy to purchase, expensive to feed, and somewhat prone to disease. In addition, they require cold water (below 70 F) in order to thrive. As a general rule, these trout do well only in waters that are too cold for rearing most other kinds of fish, and will not even survive in locations suitable for "warm water" fish. (In parts of the south, though, commercial growers take advantage of this trait by raising catfish in cages in the summer ... and then using the same enclosures to produce a winter crop of trout!)

Sunfish: The bluegill (Lepomis machrochirus) is known to be a good cage culture fish, and other sunfishes may also turn out to be suitable. Indeed, various hybrids—that grow much faster than the wild species are already beginning to be available commercially ... but they're still quite costly.

Carp: The much-despised common carp (Cyprinus carpio) is, in fact, a tasty food fish and one of the easiest and least expensive to feed. In my experience, the commercially available "Israeli" or "mirror" variety does best, although unselected wild stock can be raised.

American eels: It may surprise you that baby eels (Anguilla rostrata) are captured in U.S. estuaries and exported—fetching a handsome price in the process—to Taiwan and Japan. .. where they're "grown out", often in cages, and used for food. There's no reason we couldn't raise this gourmet food ourselves.

Tilapia: If you can maintain a pond water temperature of at least 75 F for four months or more, you might want to consider raising tilapia. (I particularly recommend the blue variety, Tilapia aurea.) These fish are even more adaptable feeders than are carp, and will make good use of the opaque "pea soup" that occurs in some highly fertile waters. Take caution, though: In many states, it's illegal to import the potentially fast-spreading fish. Furthermore, growers in very warm climates should not use tilapia—or other exotic fish—if there is the slightest chance that the creatures might escape into natural or public waters.

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