Little research has been conducted on how different euthanasia methods impact stress-related biophysical and biochemical changes in fish, specifically koi.
The study assessed the effects of tricaine methanesulfonate (MS-222), clove oil, and carbon dioxide (CO) on koi by measuring time until opercular movement stopped and plasma levels of lactate and cortisol.
Results indicated that MS-222 led to the quickest cessation of opercular movement and highest cortisol levels, while CO had the slowest cessation time and the lowest cortisol levels.