Nutritional Composition of Invasive Blue Catfish (Ictalurus Furcatus) as a Diet Alternative for Piscivorous Species in Zoos and Aquariums.

Abstract

Blue catfish (Ictalurus furcatus) remain a prevalent invasive species in the Chesapeake Bay, with juveniles a common bycatch during commercial fishing operations. Rather than returning them to the water as is the current practice, these smaller-bodied fish can be harvested for niche markets, including as forage fish consumed by piscivorous species in zoos and aquariums. Baseline compositional data are useful for balanced diet formulation, determination of necessary supplementation regimens, and contributions to animal health. The nutritional value of whole juvenile blue catfish ( ~ 100 mm-300 mm total length) was determined in 9 samples collected during June from 3 separate locations in three different tributary rivers. Composition of fish varied among rivers [water content (ranging from 71% to 78%, as-fed basis), protein (50%-69%), crude fat (16%-36%), and ash (12%-20%, all dry matter basis]. Ranges approximated that of fish species commonly used in managed feeding programs, as did amino acid balance. While polyunsaturated fatty acids comprised only 22%-27% of total fatty acids measured, total omega-3 to omega-6 fatty acid ratios averaged ~1:1. Both macro- and trace mineral levels were within expected ranges for whole prey, with no indication of elevated heavy metal contaminants. Fish contained fat-soluble vitamin D and E levels averaging 4722 and 26 IU/kg dry matter, respectively, and unexpected levels of particular water-soluble vitamins such as biotin (193 mg/kg) and folic acid (648 mg/kg). Locally sourced juvenile blue catfish from Chesapeake Bay may be an alternative diet ingredient for piscivores and other carnivores, while removal simultaneously benefits local aquatic ecosystems and native species habitats.