Introduction: The CO2 Tank

Picture of The CO2 Tank

A little about myself and this instructable...

I have owned many snakes as pets and currently have two boa constrictors. And, as all creatures, they need to eat as well. My problem - I don't want to risk my snakes getting injured by killing their prey. We're not talking mice here, either. My two eat things like ducks, chickens, guinea pigs, rabbits, piglets - whatever is a good sized meal.

So I can either throw the animal in there with them alive and watch it scream and die painfully or I can euthanize the animal first to save both animals any pain.

In this instructable, I will explain how I made a carbon dioxide chamber to safely euthanize an animal before I feed it to my snakes.

Step 1: You Need Some Sort of Chamber

Picture of You Need Some Sort of Chamber

A person making a project such as this will first need a chamber with a tight-fitting lid that is big enough to fit the type of animal that the hungry snake likes to eat.

Remember to consider how big the snake can grow and to choose a container that will accept the proper-sized food for it throughout its life.

I used a metal popcorn barrel. The barrel was painted, and I drilled two small holes into it - one near the top and one near the bottom.

Take care when drilling that the hole is the proper size to accept the tubing that will be used later.

As an optional step, I cut out a hole in the lid and used epoxy to fit a scrap piece of plexiglass so that I can see inside. I have found this very helpful when administering the CO2.

Step 2: Attatch the Tubing

Picture of Attatch the Tubing

For this, I used small aquarium tubing. I fed about an inch of tubing through each hole and held them in place with epoxy. Use enough epoxy to create an air-tight seal.

The bottom inlet is for the CO2 and the top is an outlet to allow air to escape.

Step 3: The CO2 Tank

Picture of The CO2 Tank

I used a regular 20oz. CO2 tank made for paintball guns. To it, I attached a valve that controls the amount of gas released and to the valve, I connected a fitting that accepts a tube.

When I went to buy all the parts, I went to a local shop that specializes in paintball accessories and explained to the clerk what I needed and he set me up with the proper parts.

The tube connected to the CO2 tank connects to the bottom tube in the chamber.

Clarification by user french t0ast:
The part that screws onto the valve of the tank is called a "on/off ASA" (Air Source Adapter).

The output from the ASA is threaded at 1/8" NPT.
The black tube coming from the asa is called macro line.

So you would need
co2 tank
on/off asa
Macro line
Macro line fitting (1/8th)"

Step 4: The Air Trap

Picture of The Air Trap

When filling the chamber with gas, the air will escape through the top tube.

The last thing you want is for air to be able to get back in after administering the gas. To solve this, the top outlet tube goes into a cup or bowl of water. This allows the air to escape and bubble out, but it cannot come back in.

The reason why: When euthanizing the animal, oxygen leaking back in can prolong the death and also cause it to choke. In my opinion, if the animal is giving its life to feed my snakes, then it deserves to die quickly, painlessly and most of all - with dignity. I have the utmost respect the animal, same as I do for the ones that die to go on my dinner plate.

Step 5: Administering the Gas

Picture of Administering the Gas

The gas is leaked in when the valve is turned on, slowly filling the chamber from bottom to top. The animal breathes in the gas and dies. If done properly, it will look as if the animal went to sleep and it won't choke or struggle.

Start with a small flow at the beginning. Too much too fast and the animal will panic and/or choke. Once the animal seems groggy and lays down, slowly increase the flow. At this point, the animal will appear to faint. Continue with the gas until the chamber is completely full with gas. Since CO2 is clear, you will have to judge when it is full. Wait two minutes or so and add more gas. At that point, the animal is dead, but sometimes it is hard to tell. Just let it sit for about five minutes or so. After that, shake the chamber and if the animal is not responsive, then it is dead.

Take care when removing the lid. Fan it slightly with the lid or something to prevent yourself from inhaling any gas. The animal will most likely have soiled itself and a layer of bedding will make for an easier cleanup.

When doing two or more animals at one time, such as a litter of mice, take care to not overcrowd the chamber as this will stress the animals and cause panic. Administer the gas as normal.

The most important part is not to stress the animals. When done properly, the animal dies very calmly and does not choke or panic.

At this point, the dead animal can either be fed to the snake or frozen for later.

Step 6: Thoughts and Tips

Picture of Thoughts and Tips

You are a pet owner. You have a duty to keep your pet safe and healthy. Your pet can rely on nobody but you to provide it with what it needs to live.

A snake's temperament is caused by many factors such as the species and also how it is treated. Weaning a snake from eating live prey to accepting pre-killed prey can help it to become comfortable with handling and help to reduce the risk of the handler getting bitten. After all, it will no longer have to kill for sustenance. A snake is also less likely to strike when it is full. Handlers should also take care to wash off any scent of prey from their hands as a snake can easily mistake a scented hand for a meal. Check with the seller and with books to determine how often a snake will need to eat before you buy it.

Food can easily be frozen and stored for later use. It can be left to thaw on the counter and when completely thawed, warm the body with warm water. This can be done by putting the animal in a zip-lock bag and placing it in a container ot warm water for 10 or 15 minutes. Be sure that the animal is completely thawed as you do not want your snake to eat any ice. This can cause it to get sick, become too cold, or regurgitate the meal.

To convince a snake to begin taking dead prey, you can try rubbing the food on a live prey item to cover it with the scent of food. Forceps can be used to wiggle the food in front of the snake and cause it to strike. I use grill tongs for this as it keeps my hands a safe distance away from the snake when it is eating. After a while, the snake should become used to eating this way and it will become easier. I never have to scent the food anymore - the snakes are used to the food the way it is and they strike and wrap it as usual.

Last, but not least - as a responsible pet owner you are responsible for providing the snake with proper nutrition. The snake derives its nutrition from the food it eats, so the prey must also be healthy. Prior to gassing, feed the animal for a couple of days with quality food. Also, a good time to gas is after it has been observed eating. This ensures that there are extra vitamins and protein inside the animal's stomach that the snake will benefit from.

In closing, snakes don't eat tofu. An animal has to die for the other to live. But, with care and compassion, an owner can ensure a quick and painless death for the prey and prevent injury and vet bills when the live prey fights back. Most all types of snakes will accept pre-killed prey and it is easy and economical for the owner. Rats and mice come already frozen, but to a person with larger snakes (like me) or with a large collection who breeds their own food, this is an easy and economical way to euthanize prey.

Step 7: Additional Info

Picture of Additional Info

To read more on the subject of humane euthanasia of feeder animals, you can read what the American Veterinary Medical Association has published:
AVMA & humane euthanasia

or from the University of Iowa:
University of Iowa Animal Research

Guidelines for the Euthanasia of Rodent Feti and Neonates
Yale University's IACUC co2 euthanasia guidelines
University of California's euthanasia guidelines

Please note that these guidelines apply mostly to laboratory animals, as some mention the use of barbituates and other gases. But, the CO2 method is widely practiced and acceptable as a rather humane way to euthanize small animals.


Jeni8115 (author)2016-09-08

Hi, my son just got a 5 year old female ball python 2 days ago as a rescue. She has always eaten live food. Is it too late to try frozen? Thank you in advance for any advice you may have. Hope you have a great day! :)

KharisD (author)Jeni81152016-12-19

It's never too late for swapping to f/t. It will be much easier to swap to freshly killed first until you can move to fully frozen ones.

TelesforoR (author)2016-10-26

my question is it dangerous to touch the hose when co2 is flowing through it?

Richie15 (author)2009-10-03

The CO2 method is far from perfect. Hold your breath for as long as you can, or breath in and out of a plastic bag for a while. Feel that pain in your upper chest and your head? That's not oxegen deprivation, it's CO2 intoxication. If you can find a canister of N2 (nitrogen), this will give the same result (i.e. a dead animal) but more humanely. If you're gonna ignore me and stick with the CO2, you're as well off drowning it, save you buying any gas at all. Having said that, I do agree that your way is more humane than most poisons, which can then be transferred to the snake too.

 Liquid nitrogen is easier and cheaper if you can find it, most colleges and universities will sell it for about $2 a liter and you can carry it in a thermos. You could just put it in a sealed container and run a tube from the container to the gas chamber. Since the suffocation response is entirely controlled by CO2 levels, replacing all the CO2 and O2 in the chamber with N2 will cause the animal to pass out and die just from lack of O2, completely painlessly.

i know this post is years old but im still hoping for a reply, if i use the CO2 method or N2 to kill feeders rats for my ball python, it doesnt hurt my ball python to eat the poisoned rat does it...?

Nope, not any different than if you had drowned it.

 Yep, that's what I was getting at. Just didn't realise it was so easy to get, thanks! :)

ineedsnakeadvice247 (author)2016-08-23

I know this post is years old, but i really need help, so if i use this method, and feed the poisoned rat to my snake, it wont hurt my snake, right?

Nope it won't hurt your snake. Also, the rat isn't "poisoned" - it's just been suffocated with carbon dioxide (which we all exhale naturally).

This is a good way to feed your snake without it getting hurt. Good luck.

Nyanman (author)2013-01-13

Interesting...How does this compare in price and ease to buying commercial prekilled food?

iPodGuy (author)Nyanman2013-01-14

Buying commercial prekilled food is easy and convenient if you have 1 or 2 snakes. Especially if the snakes aren't very big.

I had several snakes back when I did this, and the boas were rather large. I started breeding mice and rats and used them to feed my snakes and sold them to other friends of mine to make some money on the side. Also, my boas liked food a little larger than rats, so I would buy rabbits, guinea pigs and other food for really cheap at an animal auction. They were live, so this is the way I would euthanize them.

I'm married now, so I had to give up my snake hobby.

The Fishfrog (author)2009-03-01

Cute snake! Personally im a lizard guy but i still love snakes(and all reptiles).

freeza36 (author)The Fishfrog2011-12-24

one time found a 5 lined skink back behind my house. i kept him for about 3 weeks, but he refused to eat so i let him go

hungyhipo 2 (author)2010-10-17

My friend has a ball python and the things are freaking awesome. The night i slept over they feed the snake and it was cool but i kind of felt bad for it. Are there any other less expensive ways to do this

freeza36 (author)hungyhipo 22011-12-24

ball pythons tend to go long periods without eating, especially when you first get them

iPodGuy (author)hungyhipo 22010-10-19

Yes. You can buy the mice already frozen. They're typically cheaper than live mice and they can be stored in the freezer. It's convenient also because you can buy 10 or a dozen (or more) at once instead of running back to the pet store every week.

To thaw the mouse properly, don't leave it on the counter or something to defrost. Just put the frozen mouse in a ziplock baggie and place it in a sink full of warm water. Once the mouse is completely thawed and thoroughly warmed, you should be able to feed the snake.

Ball Pythons are well-known as finicky eaters, so don't be discouraged if it is difficult to get it started on frozen/thawed mice. I was successful with mine.

If you need any other tips, let me know.

hungyhipo 2 (author)iPodGuy2010-10-19

i think i heard them say that they will only eat live mice

i dont know though so i will ask him today

iPodGuy (author)hungyhipo 22010-10-20

Has he tried F/T mice?

If your friend decides he wants to try to switch, I will be happy to offer advice.

hungyhipo 2 (author)iPodGuy2010-10-20

I talked to him yesterday, he says they only eat live mice. What are f/t mice

iPodGuy (author)hungyhipo 22010-10-21

F/T = Frozen/Thawed

hungyhipo 2 (author)iPodGuy2010-10-21

thats what i thought. Im going to talk to hi today

freeza36 (author)2011-12-24

that is a beautiful red tail boa

steam_cannon (author)2010-12-27


* Simply use canned air for cleaning keyboards. Inject the gas into a small hole in the lid of the container. It's heavier then air so it will displace the air and fill the container. Then no valves or tubing is required.

* Or make CO2 using vinegar and baking soda in a tall pitcher then pour the CO2 into the other container. To test that it works, put a tea light candle in the larger container. The candle will go out.

nickdisney (author)steam_cannon2011-10-04

i know this is a dead post, but i would not recommend using canned air, or "dust off" they contain a propellant, the refrigerant 1,1-Difluoroethane. This crap stays in the blood stream and can lead to some complications in the snake. besides that, the prey would be high and panic before death. don't forget, whats good for the snake is good for the prey.

steam_cannon (author)nickdisney2011-10-22

In animal studies 1,1-difluoroethane causes reduced aggression/excitement and diffuses away in minutes.

It doesn't stay in the blood forever. So everything you just said above is at best mostly wrong. It's certainly true that carbon dioxide is more natural, which is why I recommended it too. But realistically difluoroethane should be equally safe. Many gases are used in the treatment of meat such as carbon monoxide, but the gut is good at dealing with toxic gases like carbon monoxide and other mixes of methane and even sulfur dioxide. And since difluoroethane diffuses out of living organisms very quickly, if it was absorbed by the gut it would only be absorbed very slowly. So I don't think it's likely that traces of diflouroethane in a treated food animal is going to harm the snake. It should be perfectly safe.

BadFJCruiser (author)2011-04-17

I have a Spider phase Ball Python ,I feed him in a plastic shoe box never in his enclosure ,i put a live mouse in box lower him in he attacks mouse while still in my hand ,I feed him every Saturday hasn't skipped a meal yet ...

DrWeird117 (author)2010-11-18

Huh...reading this, I can only think that my old python died because of me.

Allycion (author)2010-04-01

At the risk of being laughed at for jumping off the snake subject... I was wondering if this setup could be scaled up slightly for the humane processing of meat rabbits?

I have been taking mine to a butcher that specializes in deer and small game but it gets rather expensive after a while. I was thinking that this might work.

Also, would the CO2 / N2 leave any traces in the meat that would make them bad for eating?

Charlie24601 (author)2008-02-14

Any chance you could elaborate more on everything you need for the CO2 cannister? Also, thanks for telling us about the outlet tube and how to properly use this. I actually recently bought out a small pet store and the previous owner seemed to have problems with her CO2 chamber due to panicing and slow deaths. Havn't needed to use it yet (mouse colony is still too small), but this is all good info.

iPodGuy (author)Charlie246012008-02-14

I'll quote myself from a post a little bit lower down: OK, I'll try to describe them since I don't know what they are called. I bought two new tanks at Wal-Mart. I took them to a paintball store and told the clerk what I was planning to use it for and what I would need to have. He gave me a valve that fits over the threads of the tank. The valve screws downward and depresses the button on the tank. There is a threaded hole in the side of the valve that the gas escapes through. Into that threaded outlet, he put in some sort of coupling that grips the black rubber straw looking-thing in the picture. That's what I bought. The aquarium tubing that I used fits over the black straw. Maybe a paintball hobbyist can chime in with the exact names of the parts, but really, if you do what I did any knowledgeable clerk will be able to assist you.

imthatguy1125 (author)iPodGuy2010-02-11

So is it regulated

iPodGuy (author)imthatguy11252010-02-12

The valve I describe allows you to manually control the amount of CO2 going into the chamber.  There is no gauge or anything, but I'd guess one could be integrated into the setup. Is that what you wanted to know?

imthatguy1125 (author)iPodGuy2010-02-13


French t0ast (author)iPodGuy2009-10-31

The part that screws onto the valve of the tank is called a "on/off ASA" (Air Source Adapter).

The output from the ASA is threaded at 1/8" NPT.
The black tube coming from the asa is called macro line.

So you would need
co2 tank
on/off asa
Macro line
Macro line fitting (1/8th)"

Russian sniper (author)2010-02-04

my snake died a cause of the co2
haha just kidding
its easy to do

shadeaux (author)2008-06-15

Never use a microwave to thaw or heat frozen mice.Not only can it cause them to explode, but it can also begin a cooking process which is NOT good for your snake. Thaw them under warm(not hot)water. And if your snake is finicky, you may want to try thoroughly washing the frozen critter,as it's thawing. Not only does this wash off any germs that may be on the skin, but it removes the smell that may be there from the freezer, or from old urine/feces on the fuzzy critters when they were originally frozen.This tip originally came from the breeder that I bought my last two snakes from- and it has never failed.

Sometimes when my snake doesn't want to eat, we sprinkle some chicken broth on the mouse.This keeps him rather occupied in the tank as he grooms himself and doesn't see my ball python coming at all.Don't drown the little guy, just sprinkle.I've heard this works well for getting snakes to eat thawed mice too. Hell, he even started smelling good to ME, jk :)

RadBear (author)shadeaux2008-08-04

Punch holes in them with a fork and they won't explode when you microwave them.

jellybean10122 (author)RadBear2009-02-19

lol, your talking about them as if they were sausages or something. ill have to try that! (jokes) does it work, if so, i s'pose its okay. i dont know of any detrimental effects microwaving food can have to the herp.

downgrade (author)RadBear2008-08-23

Or just use hot water since its much smarter to do...

RadBear (author)downgrade2008-08-25

Smarter but not as fast. We were always pressed for time at the wildlife rehab place I volunteered at so we would do water if we had time, but sometimes just zapped them in microwave.

downgrade (author)RadBear2008-08-25

I'm confused as to what you mean "if we had the time", you can thaw several animals at the same time, and secondly I don't know of anything that eats frozen food that has to eat in a 15 minutes time frame. Punching holes in them runs the risk of them leaving a large mess behind after being devoured, which runs some sanitation risks. I suppose if you've been fortunate enough that you hadn't had problems that's your own prerogative. I just find it easy to multitask while letting some mice thaw out under hot water, and then have less of a chance of finding gore in the feeding tank.

RadBear (author)downgrade2008-08-25

Typically we had a great many animals to weigh, medicate, clean their cage and feed. Since it was an all volunteer staff and little to no organization/coordination getting the shift before to thaw the mice and rats for the hawks the next day was unlikely. The sanitation risk was low b/c the cages were cleaned daily. I can definately understand why someone wouldn't want that in their pet's cage though.

downgrade (author)RadBear2008-08-25

Ok ok, touche :P didn't think about birds of prey, making me a jerk. Any way, as I said its your prerogative all the same, but what I meant (I am a little sleep deprived, one of those inspiration nights last night i guess) is that if it works for you that's fine, but keep in mind there are plenty of other people taking tips here, and just because they made an instructable on advanced robotic programming, doesn't mean they have common sense (hell, look at me). So in other-words I think I was kind of being a jerk and I apologize, but also you still gotta be careful with microwaving, especially depending on what you are feeding. A constrictor snake can make quite a mess (even if you don't pop holes in it) and it can be a pain to clean (i know someone who tried this). However I have never fed, nor seen something like a hawk fed, so you win that round. But for the majority of the people, they can do whatever they want (sometimes a sad fact) but for things that live on the ground, especially in substrate, I would vote against creating any more possibility of insides becoming outsides because cleaning takes a lot longer then thawing in hot water. Again, all just opinions.

RadBear (author)downgrade2008-08-26

Cool. Just looking at the same thing from different points of view and arriving at different conclusions. Typical human condition. :)

downgrade (author)shadeaux2008-08-23

The urine and feces will actually entice the snake to eat the mice, thats the smell its looking for when it looks for food. That's why sometimes people who buy frozen will have the mice rubbed around in old hamster/mice bedding...

Shagglepuff (author)2009-08-07

At first I thought that this instructable was about how to feed a snake CO2...

bounty1012 (author)Shagglepuff2009-08-17

LOL me too.

jongscx (author)2008-02-12

You brought up an interesting point though... Can a snake eat tofu? could you compress it into a mouse-like shape, add some frilly stuff to simulate hair, and smear it with chicken bullion cubes? Anyway, I just wanted to throw a tip my friend told me about. He said that initially, his snake was accustomed to eating chicks and so wouldn't eat when he switched to mice. He dipped the thawed-frozen mice in chicken broth and got the snake to eat it. Not sure if it's valid of he was BSing me (he was known to do so often)...

About This Instructable




Bio: Just your average handyman.
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