Enzymatic Dechorionation of Goldfish, Walleye, and Northern Pike Eggs

Abstract

Removal ofthe chorion from fish eggs facilitates observation ofpiscine embryogenesis and allows efficient microinjection during gene transfer protocols. Several treatments were screened to evaluate their effectiveness in removing the chorion from newly fertilized eggs of goldfish Carassius auratus, walleye Stizostedion vitreum, and northern pike Esox lucius without destroying egg viability. Goldfish eggs dechorionated in 2.5 mg/mL trypsin showed excellent viability. No effective procedure for dechorionation of walleye eggs was found. Northern pike eggs could be dechorionated in 0.6 mg/mL protease type XXV, but mortalities above 50% were commonly observed.