Mississippi State University scientists looking to help catfish producers keep costs low and quality high have discovered that catfish can thrive for the first six weeks after hatching by feeding on naturally occurring zooplankton.
Several aquaculture researchers at Mississippi State's Thad Cochran National Warmwater Aquaculture Center compared the growth and survival of two groups of recently hatched catfish, called fry. Both groups were raised in ponds, but for six weeks, one group ate commercial feed daily, while the other group did not.
"Postponing the use of specially prepared commercial fry feed for six weeks showed that fry are relying on naturally occurring microscopic food organisms such as zooplankton," said Charles Mischke, aquaculture research professor at Mississippi State's Delta Research & Extension Center in Stoneville, Miss.
Fry that were not fed a supplemented feed for six weeks grew as well as fry that were given expensive fry feed. Producers usually supply a specially formulated, high-protein fry feed once or twice daily for six weeks.
Zooplankton are a natural food source for fry that are high in protein and other nutrients and are abundant in ponds and other bodies of water, Mischke said.
"This work shows that fry thrive on natural pond productivity during the first four to six weeks of growth," said David Wise, coordinator for the Thad Cochran National Warmwater Aquaculture Center in Stoneville and a researcher with the Mississippi Agricultural & Forestry Experiment Station. "Reducing or eliminating fry feedings during this time can reduce some of the cost of fish production. Implementing this practice can save fingerling farmers at least $236 per acre on initial feed costs."
Wise said the study also shows the importance of promoting the growth of zooplankton communities in ponds as a natural food source. High levels of zooplankton can be maintained through proper pond and fertilization management, he said.
"Optimizing zooplankton communities by implementing a regimented fertilization program can save producers money by reducing feed cost during the initial stages of fry production," he added.
Mississippi is one of the nation's leading suppliers of catfish fry. Last year, the state's catfish fingerling and fry sales totaled $7.7 million.