Eastern New Mexico University (ENMU) assistant professor of biology Dr. Jesse Filbrun has quantified the contribution of zooplankton to channel and hybrid catfish growth in aquaculture ponds.

Filbrun, who worked with colleagues in Stoneville, Miss., will have his research published in the August edition of Aquaculture, an academic journal focused on international scientific contributions to aquaculture, according to an announcement from ENMU.

Historically, most catfish producers rear juvenile catfish in ponds by supplying excessively large quantities pelleted feeds from the time of pond stocking. However, in 2014, Filbrun and his doctoral adviser, Dr. David Culver, published a paper in Aquaculture that provided strong evidence that live zooplankton — not pelleted feed — supported fish growth during the early weeks after stocking ponds, ENMU said.

Filbrun's doctoral research program at The Ohio State University was on improving channel catfish production reliability in ponds.

"This is an important finding because fish farmers may produce fish more cheaply, sustainably and reliably by reducing feed additions to ponds without reducing fish growth," Filbrun said.

Filbrun explained that he met with colleagues in Mississippi in 2015 to discuss a pond experiment to "quantify the contribution of zooplankton and pelleted feed to juvenile hybrid catfish growth. This study was important because the diets of hybrid catfish, which are a first-generation cross between a female channel catfish and male blue catfish, were unknown. To rear juvenile hybrid catfish efficiently, we sought to determine how much (or how little) pelleted feeds should be added to ponds by producers."

The experiment was performed in 2016 at the Thad Cochran National Warmwater Aquaculture Center in Stoneville. Filbrun said the research team used a mass-balance stable-isotope approach to quantify the fish diets, because that approach "is based on the principal that the fish tissues match the stable carbon and nitrogen isotope ratios of the foods they eat in the ponds."

According to Filbrun, the most important results of the study were that :"(1) hybrid catfish and channel catfish both rely heavily on zooplankton to support their growth during the early weeks after stocking fish in ponds, and (2) there were no differences in fish diets or growth rates between these catfish genotypes. Thus, producers should manage ponds to support adequate densities of zooplankton, and hybrid catfish nursery ponds can be managed similarly to channel catfish nursery ponds."

Filbrun's research article is available here.