Aquaculture
Aquaculture is where people, food, water, and ecology meet. New Alchemy explored aquaculture as a way to produce food from small-scale, local water sources: fish in cages in wild ponds, in ponds dug in the ground, in solar ponds above the ground, and in-ground ponds in greenhouses.
Rearing of fish in floating cages in natural ponds, lakes, and river is growing in popularity in the U.S. The advantages are that the fish are very easy to feed and harvest, their wastes are removed by natural currents, and on occasion the fish enjoy wild foods from the natural environment. With cage culture, anyone with access to unpolluted standing water can potentially grow fish for food or for sale.
Aquaculture: nutrient recycling
Today the Green Center is promoting studies of oyster culturing in coastal ponds and estuaries as part of regional wastewater treatment.
Oysters live by constantly filtering water, using the algae created by nutrients in the water as food. Recent studies of oysters in coastal ponds show that they not only produce valuable food, they are also extremely efficient in removing excess nutrients from the water, thereby improving water quality.
Aquaponics
The most sophisticated version of solar pond aquaculture at New Alchemy was an aquaponic system developed by Ron Zweig. Fish are grown in a solar pond and lettuce grows hydroponically on the surface. For more information, please read An Integrated Fish Culture Hydroponic Vegetable Production System by Ron Zweig, from Aquaculture Magazine, May/June 1986.
An advantage of this system is its structural simplicity: no electric water pumps, no water pipes, no filters, no clarifiers, no plant rooting media, etc. It is a modular, mobile unit. They have worked successfully both outdoors and in greenhouses.
For more information about growing fish and vegetables in solar ponds, read Earle Barnhart’s summary of Zweig Pond Aquaponics.
Solar pond aquaculture
Fish and algae growing together in a solar pond create an aquatic ecosystem that does not exist in nature. A solar algae pond ecosystem has high light levels, rapid cycling of nutrients, and a unique biochemistry driven by daily sunlight pulses.
The ponds act as giant test tubes for research as well as tanks for practical fish production. A major research effort of New Alchemy has been to scientifically develop methods to optimize fish production at home and on a community scale.
For more information, please read A Summary of Fish Culture Techniques in Solar Algae Ponds. This highly condensed summary explains how to optimize aquaculture in a solar pond, based on years of careful research, experimentation and monitoring: a priceless collection of practical aquaculture knowledge.
Heat storage in solar ponds
The water in solar ponds warms up when the sun hits them or when the air around them is warmer than they are. In a greenhouse they collect and store solar heat during the day and release it later at night into the greenhouse air.
A pond will release heat whenever the water is hotter than the air around it, often for several days during sunless cold conditions. It’s passive and automatic – no fossil fuel, no machinery, no sound of fans. For more information, read Solar Ponds for Heat Storage by Earle Barnhart.
Alternative fish feeds
Successful aquaculture and aquaponics depend on a population of fish that are regularly fed, like any other livestock. Standard commercial fish feeds are pellets containing protein from endangered, depleted populations of ocean fish such as anchovies.
To be sustainable, aquaculture must look to alternative fish feeds such as insects, earthworms, and high-protein plant leaves such as comfrey and alfalfa, feeds that have been tried successfully at New Alchemy. For more information, read the following publications:
- Alternatives to Commercial Feeds in the Diets of Cultured Fish
by William O. McLarney & Jeffrey Parkin
Journal of the New Alchemists
Vol. 7, 1981, pp. 74-82 - Open System Fish Culture
by William O. McLarney & Jeffrey Parkin
Journal of the New Alchemists
Vol. 5, 1977, pp. 89-92
Early computer modeling
How many fish can you put in a 700-gallon tank? How much food do you give them? How much food is too much food? How much fish that you can grow in a pond in a year?
To answer these questions, New Alchemy researchers began a scientific quest to understand the production potential and ecological limits of small-scale aquaculture. The effort of learning enough to make this early computer simulation resulted in learning enough to maximize practical fish production!
For more information, read Computer Simulation of a Solar Pond by Earle Barnhart.
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