It is recommended that dose rates of approximately 10 times the induction dose of the drugs listed above are used by immersion for euthanasia. Fish should remain in the solution for at least 60 minutes after respiration (opercular movement) has ceased and the absence of a heartbeat confirmed using a Doppler probe or by ultrasound scanner. In cases where tissue samples are required for histopathological examination, euthanasia can be completed when opercular movement has stopped by performing a secondary procedure (e.g. cervical section and pithing, or intravenous injection of pentobarbital (60-100 mg/kg)). Oil of clove (clove oil, eugenol) (500-1000 mg/ml by immersion or undiluted 10 drops/l by immersion) is available without prescription at most pharmacies and can be used by owners for emergency euthanasia. The oil must be whisked vigorously into the water to improve its solubility. It is at the veterinary surgeon’s discretion as to whether to provide direction to owners regarding emergency euthanasia at home.