Processing

Pre-harvest Planning

When catfish begin to reach the target weight, producers should start the process of scheduling harvest. The first step is to submit a sample of fish from the pond to processors for flavor check by experienced “taste testers.” Only those ponds with acceptable flavor are scheduled for harvest. The two most common “off-flavors," geosmin and 2-methylisoborneol, are secondary metabolites produced by certain bacteria and algae. These flavors are not harmful to consumers but impact product quality. Typically, fish are checked for flavor quality 3 to 4 consecutive times before harvest and processing: two weeks before harvest, the day before harvest, and the day of harvest. If the catfish are positive for off-flavors at any point in this process, they are refused by the processor and taken off the schedule until the condition improves. Fish are taken off of feed 2 to 3 days prior to harvest to purge the gut and reduce stress during harvest and transport. Any fish that might have been treated with veterinary drugs are not harvested until established clearance times have been met.

Processing operations

Catfish processing is a complicated operation and product quality is determined by the success of each successive step in the process. The entire processing procedure occurs in less than 30 minutes.

Live fish are transported to the processing plant in live haul tanks. Upon arrival, each shipment is rechecked for off-flavor. If accepted, fish are moved to holding tanks in the receiving area or held in the live haul tanks until needed for processing. As fish are moved into the facility, they are exposed to a low voltage electric current to stun the fish. Stunning permits a more humane method of slaughter and protects workers by making the fish easier to handle.

After stunning, fish are deheaded and eviscerated. Heads and viscera (offal) are moved to collection areas outside the processing area. (Most offal is rendered to make fish meal, which is used in animal and pet feed.) Fish are skinned by passing the skin side of the carcass across a mechanical skinner. While undersized or oversized fish require being filleted by hand, most catfish are filleted mechanically. Each fillet contains a belly flap (nugget) that is removed by hand. After skinning, fillets and whole dressed fish are immersed in water maintained that is below 41° F. Fish products are then size graded and sorted.

The most common product forms include whole dressed (headed, eviscerated, and skinned), steaks (cross-section cuts from larger fish), shank fillets (boned sides of the fish with belly section removed), nuggets (boneless pieces cut from the belly section of the fillet), and strips (boneless fillets cut to various lengths and thicknesses). Some products may also be seasoned or battered and breaded.

Once processing is complete, products are either packaged on ice or individual quick frozen (IQF). All products are packaged in wax lined cardboard boxes, weighed, and labeled. Product is either stored frozen or chilled on ice.

Food-safety regulations

U.S. catfish processing facilities are subject to inspection by the USDA Food Safety Inspection Service. The 2008 and 2012 Farm Bills amended the Federal Meat Inspection Act to include fish of the order Siluriformes. Channel catfish and hybrid catfish belong to the order Siluriformes.

SRAC Publications

Processing Channel Catfish
https://srac.tamu.edu/serveFactSheet/25

Processed Catfish: Product Forms, Packaging, Yields and Product Mix
https://srac.tamu.edu/serveFactSheet/26

Small Scale, On-farm Fish Processing
https://srac.tamu.edu/serveFactSheet/101

The HACCP Seafood Program and Aquaculture
https://srac.tamu.edu/serveFactSheet/173