BY Julie Speed
Contributing Writer, Delta Business Journal

  STONEVILLE - Catfish ponds are not point sources for water pollutants and have even improved the downstream water quality in many cases, say aquaculture specialists.
  “Over the last six or seven years, we’ve looked at characterizations of discharge of water from catfish ponds and have found a very low number of possible pollutants compared to how much food is produced,” said Craig Tucker, a fishery biologist with Mississippi State University and director of the Southern Regional Aquaculture Center at the Thad Cochran National Warmwater Aquaculture Center in Stoneville.
  “The way catfish ponds are managed now, they’re used for years and years without drainage,” he said. “Because the level of water is generally kept below the level of the overflow device so that there’s room for storage, and unless there’s an extremely heavy rain, the water is captured and used to offset the need to pump water into the pond. It doesn’t run out of the pond. For these reasons, discharge is really a small issue. By holding water, you give the ponds a lot of time for natural processes to clean up the water. The pond itself becomes its own waste treatment plant.”
  Of all the nitrogen and phosphorus put in the ponds as part of the feed - the only issue in pond effluents - over 95% is removed through natural processes, Tucker said.
  “When we looked at this, it was interesting to discover that the time of year the catfish ponds would have the largest effect on streams is in the summer when water flow is low,” he said. “At that time, there’s not going to be excess water discharged anyway. Last summer, when there was a drought, there was essentially no water discharged.”
  Stream water quality becomes degraded when erosion occurs during heavy rains anyway, Tucker said.
  “The timing and the volume of water released shows us that there’s very little impact on streams and rivers,” he said. “A researcher in Alabama looked at water quality variables and its impact upstream and downstream from catfish ponds. The study found there was very little difference, nothing consistent. In fact, sometimes, water quality was improved downstream
from the ponds.”
  Very few chemicals are used in the pond, Tucker said.
  “Herbicides are generally too expensive for farmers so they manage the pond so they don’t have to use them,” he said. “There are no pesticides or insecticides used. Actually, because of the expense of medication, most farmers don’t use antibiotics, either. There’s very little input of chemicals in the water. Most ponds run for years and years with nothing added because it’s just too expensive.”
  The bottom line: catfish farming is a very clean animal food production system, Tucker said.   “Catfish farmers work very hard to maintain adequate water quality for aquatic life in the pond to keep fish alive,” he said. “Obviously, the water quality in the pond has got to be pretty good to raise that crop. Just that logic alone tells us the discharge of the water is not going to have that much impact on the stream.”