Fish Farm with Cages!

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Aquaculture ... for many people, this word conjures up images of technologically complex artificial fish-rearing pools (or at the very least, large ponds devoted exclusive ly to raising fish). Yet one of the most convenient forms of intensive home-scale fish production is probably best called cage culture... and, put simply, is the practice of growing food fish in floating cages! This uncomplicated technique is most commonly used in North America by commercial fish farmers, but—as years of successful experimentation at the New Alchemy Institute farm in Hatchville, Massachusetts have shown—it could be employed by any individual who has access to an appropriate natural or artificial pond or lake.

Furthermore, the number of fish that can be produced in a single floating cage is astonishing. The current records for rainbow trout, channel catfish, and common carp—three oft-reared species—are all approximately 15.6 pounds per cubic foot. Therefore, a cage that's only three feet on a side (totaling 27 cubic feet) could conceivably be used to raise over 400 pounds of fish! And in more practical terms, even a first-time grower should be able to achieve harvests of nearly four pounds per cubic foot ... producing 100 pounds of fish in a 27-cubic-foot cage.

HOW CAGE CULTURE WORKS

To understand just how fantastic that rate of production is, imagine a 3' X 3' X 3' hole—filled with water—in your back yard. Then visualize 100 pounds of fish swimming around in it. That's the "beginner's yield" we're talking about!

Most people are aware that actually trying to produce fish in a small hole would create serious problems long before that 100-pound harvest could be achieved primarily because the creatures' wastes— along with any uneaten feed—would soon, drastically pollute the water. If such contamination didn't kill the fish outright, it would certainly retard their growth.

Of course, you could improve water quality and stock growth by using some combination of costly circulation, aeration, and filtration technologies. Cage culture, however, solves the problem of pollution in a small space ... because there is a constant exchange of water between the screen-walled cage and the larger body of water in which it floats. After all, , even landlocked, sup posedly stagnant ponds have some natural circulation as a result of wind and convection currents, but the major source of water movement in a cage is often a "natural pump" . . . the swimming and breathing of the fish themselves! Since the stock's containers are, in addition, normally floated in the upper layer of water that's at least 6 feet deep—where there likely are relatively few other fish and little organic decomposition—the incoming fluid is usually clean and rich in oxygen.