Curtis G. Byrd
Patrick Kroboth
Freya Elizabeth Rowland
2026
<p><span>Bighead carp (</span><i>Hypophthalmichthys nobilis</i><span>), black carp (</span><i>Mylopharyngodon piceus</i><span>), grass carp (</span><i>Ctenopharyngodon idella</i><span>), and silver carp (</span><i>H. molitrix</i><span>) have spurred wide concern of potential ecosystem disruption as they threaten to invade the Laurentian Great Lakes. Besides competition for resources, carp may also have disadvantageous nutrition for predators. One biochemical aspect to consider in carp is production of the enzyme thiaminase that cleaves thiamine (vitamin B</span><sub>1</sub><span>), making it unavailable to most vertebrates. The function of thiaminase within prey fishes is unclear, but roughly half of all fishes tested have measurable thiaminase activity. Predators consuming large volumes of prey with high thiaminase activity can develop thiamine deficiency, ultimately leading to offspring mortality. Three invasive carp (black carp, grass carp, and bighead carp) have no published thiaminase data. We tested juvenile (<160 mm standard length) black carp (n = 38), bighead carp (n = 7), grass carp (n = 50), and silver carp (n = 50) for thiaminase activity. All four species had measurable activity; however, grass carp had statistically higher thiaminase activity (p < 0.001; median = 61 nmol/g/min) than the other three species. Silver carp had the second highest thiaminase activity (14 nmol/g/min). Bighead (2.7 nmol/g/min) and black (2.2 nmol/g/min) carp had the lowest thiaminase activity; activities were often near detection limits. Predators with diets heavily composed of grass carp or silver carp may experience thiamine deficiency, though seasonal variation in carp size and other food source availability may determine potential effects of invasive carp predation in Great Lakes food webs.</span></p>
application/pdf
10.1016/j.jglr.2026.102751
en
Elsevier
Thiaminase I activity is high in grass and silver carp, but negligible in bighead and black carp
article