Efficacy and antiparasitic mechanism of 10-gingerol isolated from ginger Zingiber officinale against Ichthyophthirius multifiliis in grass carp.

•Three anti-Ichthyophthirius multifiliis compounds were isolated and identified from ginger.•10-gingerol showed the highest efficacy against I. multifiliis in vitro and in vivo.•10-gingerol was effective in treating infected fish at a concentration of 4 mg/L.•The antiparasitical mechanism of 10-gingerol was investigated and demonstrated.•10-gingerol had potential to be used as a therapeutic agent against I. multifiliis.