Table 1.

Advantages and Disadvantages of Different Euthanasia Methods for Zebrafish

	Advantages	Disadvantages
Concussion/percussive blow to the head	Fast No residues Simple device	Uncertain performance Infeasible to study the brain Not appropriate for zebrafish due to their small size Not applicable in embryos or larvae
Electrical stunning	Rapid and reliable	No adequate methods and devices available for zebrafish
		Muscle tissue potentially damaged by contortion
		Not applicable in embryos or larvae
Anesthetic overdose	Extensive experience available Many substances to choose from	Aversive reaction of animals (stress reactions) to virtually all tested substances
		Chemical contamination (potential chronic exposure) Environmental protection Impact on experiments Personnel safety
		Necessitates increased cleaning due to chemical residues (oily properties) increasing costs
		Effect/results slower than with other methods
		Difficult procurement and disposure for controlled substances
		Low effectiveness in embryos and larvae
Rapid cooling	Fastest procedure (seconds)	Not suitable for surgical interventions Might not be effective with all fish species, in particular larger species or nontropical species Not reliable as singular method in embryos
	Brief stress period
	Reliable (no recovery of vital functions)
	No chemical contamination (environment, personnel, animal, experimental safety)
	Safe to personnel
	Simple procurement and disposal