Things You'll Need
- CO2 tank
- CO2 release valve
- Remote (hose that connects the CO2 tank to the plastic container)
- Remote adapter
- Tall plastic container with a tight-fitting lid
- Aquarium hose
- Jar
- Epoxy sealant
- Drill
- Water
- Paper towels
- Plastic baggies with zip-lock seal
Instructions
Drill two holes in the plastic container. One should be near the bottom and large enough to hold the remote adapter. The second hole should be toward the top and an appropriate size for the aquarium tubing. This container will be the kill tank.
Attach one end of the remote to the CO2 tank. Attach the other end to the remote adapter, then place the adapter in the bottom hole of the plastic container. Squeeze epoxy sealant around the adapter both inside and outside the kill tank to ensure that it is an airtight connection. Allow the epoxy to dry.
Fit the aquarium tubing into the top hole of the kill tank. Thoroughly seal with epoxy and let harden. Put the other end of the tubing into a jar full of water. During euthanasia, this tube allows oxygen to escape, so the kill tank can fill with CO2.
Place paper towels in the bottom of the kill tank, then add mice. The paper towels will absorb urine during the euthanasia process. Don't overcrowd the mice unless you want a messy clean-up job. Tightly close the top lid.
Slowly turn the CO2 tank on by slightly rotating the top valve clockwise. Watch for the mice to slow down and appear to fall asleep. Once they appear to be sleeping, turn valve on the CO2 tank again to flood the kill tank with gas. Turn the CO2 off and allow the mice to sit in the tank for at least five minutes to ensure that they are dead. You may wear a facial or gas mask if you like; however, there is little danger to yourself as CO2 is heavier than oxygen. Even if some CO2 escapes the kill tank, the CO2 will sink, and plenty of oxygen will still be available for you to breathe.
Bag the mice individually in the plastic baggies, trying to get as much air out of the bags as possible to prevent freezer burn. Then, double bag them just in case the baggie gets torn. Put them in the freezer and thaw them out as needed to feed your snake.