Catfish Farming Becoming Big in Ga.

Monday, July 24th 2000, 12:00 am
By: News On 6

TIFTON, Ga. (AP) — Catfish farming is becoming big business in Georgia, and some researchers want to help aquaculturists make even more money by growing two crops in one tank.

University of Georgia scientists think catfish growers can use their pond water to grow a profitable algae. The project, combining the fast-growing sciences of hydroponics and aquaculture, would be good for farmers and also for the environment because the plants would absorb much of the waste produced by the catfish.

``It's a demonstration of being able to raise fish and another crop with the same water,'' said Gary Burtle, an aquaculture specialist at the university's National Environmentally Sound Production Agriculture Laboratory, or NESPAL.

Paul Williams, owner of Owen & Williams Fish Farm Inc. of Hawkinsville, Ga., said Burtle's research could benefit fish producers by providing new opportunities and by helping them meet future clean water standards.

``We all have to look at diversity,'' he said. ``We can't grow all cotton. We can't grow just channel catfish. I think this would be a way to diversify.''

Researchers are growing lettuce in the catfish water, but they hope eventually to grow a more profitable algae.

Hydroponics is a way to grow plants without soil, usually in a bed of nutrient-rich water. No soil means no weeds or soil-borne diseases. Aquaculture, the fastest growing segment of agriculture, is farming aquatic organisms such as shrimp, salmon, oysters and crawfish.

Catfish production is the predominant form of aquaculture in Georgia.

For his experiment, Burtle has a large tank full of catfish. Their pellet food is rich in nitrogen, phosphorous and protein. Catfish absorb only about half the nutrients in their feed. The rest mixes with the water and is wasted.

Burtle filters water from the tank to remove sediment and then pumps it into long rectangular containers where the lettuce grows. The plants are supported on strips of plastic foam, with their roots dangling in the water.

Burtle hopes to produce an algae known as hematococcus, which is used to make beta carotene, Vitamin A, antibiotics and pigments that give chicken and salmon meat a healthy pink color. Such pigments, now produced synthetically or through a yeast process, are worth $1,000 per pound, he said.

``The bottom line is to come up with a crop other than catfish that can be raised in the same water,'' Burtle said. ``We think algae will be easier to grow than a vegetable crop such as lettuce or tomatoes.''

Hematococcus already grows wild in fish ponds. Burtle is trying to isolate pure cultures in greenish-colored beakers in his laboratory so that fish farmers can grow it.

Fish and the food they eat can elevate nutrients levels in ponds. Nutrients include nitrogen and phosphorous, which are components of fertilizers. When levels are high, they can choke a body of water with sediment and cause copious plant growth.

The hydroponics system leaves the water less polluted because plants absorb the nutrients for growth.

``We want to show how you could use catfish waste water,'' Burtle said. ``We're raising a crop that uses waste nutrients.''

Georgia fish farmers need methods for cleaning up pond water because the state is likely to follow others that have adopted ``zero discharge'' policies. They now drain their ponds before restocking, or they restock continuously in the same water.