Expand page menu
Skip to page menu

PURPOSE:  The purpose of this policy is to standardize the practices of using buffered MS-222 (tricaine methane sulfonate) for euthanasia and anesthesia of fish and other cold blooded aquatic animals, and to provide recommendations to investigators and personnel for its safe and appropriate use.



Preparation:  MS-222 is not regarded as a toxic chemical by OSHA classification but according to the MSDS, MS-222 “may be irritating by inhalation, ingestion or absorption through the skin.”  Also, some literature suggests that MS-222 is a potential mutagen/carcinogen. Therefore, whenever preparing a stock solution with the powdered form of MS-222 all work should be done in a well ventilated area (outside in the field or under a fume hood in the laboratory) and protective clothing is required.  This includes a lab coat, chemical resistant gloves (e.g. nitrile), dust mask and goggles. If work is done in a fume hood the dust mask is not necessary.  When handling the prepared solution, a lab coat, gloves and eye protection are required.

Pharmaceutical grade MS-222 must be buffered with sodium bicarbonate resulting in a pH between 7.0 and 7.5.  Two examples of pharmaceutical grade MS-222 are Finquel and Western Chemical’s Tricaine-S.


Storage:  Powdered and prepared solutions should be stored in a dark brown bottle and kept refrigerated or frozen if possible. Prepared solutions should be clearly labeled with the name of the drug, concentration, and the date that the solution was prepared. Replace solution monthly or any time the solution begins to exhibit a brown coloration.


Disposal: All preparations, including expired powder, stock solution, and diluted water baths are considered hazardous chemical waste and disposal down the drain is not an acceptable method.  Disposal and waste pickup should be arranged through Environmental Health and Safety.  https://www.uwlax.edu/ehs/.

Prepared by:  Amy Cooper

Adoption Date: 9/13/16
Amended: 7/12/17
Reference minutes: 9/13/16, 7/12/17