Summary: Zebrafish embryos develop in their eggshell (the chorion) until hatching (~48-72 hours post fertilization). Because the chorion is impermeable to water, it needs to be removed prior to metronidazole treatment and β-cell ablation in Tg(ins:NTR-mCherry) transgenic zebrafish embryos. This can be achieved either with forceps or by enzymatic removal using Pronase. The earliest time of removal should be after completion of gastrulation to avoid bursting of the yolk and potential infections.Diabetic Complication: