Correlations of xanthophylls in catfish fillets, plankton, shad and snails in catfish production ponds in west Alabama

• Evaluate xanthophyll in catfish fillets and in natural organisms in catfish ponds with and without reported incidences of yellow fillets in west Alabama.
• No correlation was found between xanthophylls in catfish fillets and in microorganism samples (20-75 microns) in catfish pond.
• Results revealed a linear correlation between xanthophylls in catfish fillets and in microorganisms (> 75 microns).
• Xanthophyll levels in catfish fillets were linearly correlated with those in gizzard shad.

Yellow coloration of catfish fillets has always been a problem. Recently increased consumer scrutiny has brought this to the forefront as a major industry concern. As catfish cannot synthesize xanthophyll, commercial feeds and natural prey items are the initial sources of the yellow color. To better understand the contribution of natural foods, a field study was conducted to identify if there were correlations of yellow fillet and natural productivity under commercial pond conditions. Upon notification from a west Alabama fish processor, yellow catfish fillets and natural organism samples (plankton, shad and snails) were collected from different farm ponds in west Alabama. “Clean” catfish fillets (no unacceptable yellow coloration) and natural organisms were also collected at multiple farms where problematic yellow fillets were not present. In addition to large food items, microorganism samples from the ponds were collected by pumping pond water through two filters (sizes 20 μm and 75 μm) for a period of 10 min. The fillet and field samples were analyzed quantitatively for xanthophyll levels through High-Pressure Liquid Chromatography (HPLC). Results revealed a correlation between xanthophyll level in catfish fillets and in microorganisms (> 75 μm). Results indicate that natural productivity consumed by gizzard shad and other filter feeders appears to contribute to the xanthophyll levels in catfish fillets.