What Size Mice and Rats to Feed Your Snake?

If this is your first time owning a snake, you have a lot of things to work out. You need to learn what and how to feed your reptile, the ideal housing conditions, how to handle it, and much more.

Today, we will discuss a particular topic: the prey’s size. Mice and rats make up most snakes’ diets, so it’s natural to use these rodents as default foods.

But how do you know whether the mouse or rat is of appropriate size, and how can you determine that?

Let’s have a look!

Factors to Consider When Choosing Prey Size

Not all rodents are ideal for all snakes. To figure out the prey’s size accurately and whether your snake can eat it, consider the following factors:

Size and Age of the Snake

This is an obvious one because the smaller the snake, the smaller the prey. You may have heard that snakes can dislocate their jaws to accommodate larger prey, allowing them to consume animals considerably larger than their heads.

This is only half true. It’s true that snakes can consume oversized prey, but they cannot dislocate their jaws. That’s because there’s nothing to dislocate.

The snake’s mandible isn’t attached to the upper jaw the same way it is in humans. Instead, it hangs on via elastic ligaments, allowing the snake to increase its bite width considerably, depending on the prey.

As a general guideline, the prey’s thickness should match that of the snake’s body at its wider point. This is typically enough for the snake to ingest the animal safely.

If it’s larger than the snake’s body, the snake’s mouth opening may not cut it.

Snake’s Natural Prey Size in the Wild

You can figure this one out by learning about your snake’s overall adult size and hunting preferences in the wild.

No matter the species, learn what your snake prefers to hunt in the wild, depending on its age and size. This should give you a clear indicator of how to select your pet’s prey size and type moving forward.

The Nutritional Value of Different Prey Sizes

You should always consider how many nutrients the snake will get from one prey.

For instance, the problem is that snakes don’t eat more than one food item per feeding session. Your snake may eat 2 mice per day, for instance, but not in the same session.

Ideally, you want to provide your snake with as many nutrients as possible in one meal. The snake will then focus on saving energy, resting, and digesting its food until the next meal comes.

Such a feeding habit also mimics the snake’s natural feeding behavior, because snakes rarely, if ever, get the opportunity to ingest multiple prey at once.

How to Determine the Appropriate Prey Size

To determine the ideal prey size for your snake in particular, consider the following tips:

  • Using the snake’s size as a guide – I’ve already mentioned this one, but it’s worth reiterating. The mouse or rat shouldn’t be thicker than the snake’s thickest body region. Snakes are thicker around their mid-section, so use that as a reference point.
  • Measuring the prey against the snake’s head – This is another good metric. The rodent should be no larger than the snake’s head. If it is, the snake may not be able to swallow it. However, remember that this one refers to the prey’s overall girth, not length. The rat can be long, so long as it’s not larger than the reptile’s head, making the snake incapable of swallowing it.
  • Consulting with a veterinarian or reptile expert – If you don’t want to take your chance and risk messing things up, rely on an expert’s input instead. You can discuss your snake’s diet and feeding method with a reptile vet or any trustworthy reptile specialist. You will get the hang of it fairly fast once you learn the basics.

Factors That Can Affect Prey Size Requirements

Not all snakes prefer or need the same type of prey, despite being similar in size.

There are several factors that influence the prey size requirements, such as:

  • The snake’s health and nutritional needs – Some snakes prefer larger prey and more frequent feeding due to their size or higher nutritional needs. Such is the case with juvenile snakes. While they can’t eat larger prey, they may require more frequent feeding to support their accelerated metabolism. Sick snakes may also have different nutritional needs, forcing you to adapt to their requirements. In these cases, you’re better off discussing the problem with a reptile expert.
  • The frequency of feeding – This is trickier to determine accurately without any outside input. Not all snakes have the same feeding frequency requirements, despite being of similar size. Overall, adult snakes eat less frequently than smaller ones but require larger prey. Younger snakes eat more often and will do fine with smaller prey.
  • The presence of other prey options – While snakes prefer mice and rats as their main nutrition source, they can consume a variety of other animals, if available. These include other reptiles, birds, and other smaller mammals as well. If you have multiple live prey options available, you may want to hold back on the prey’s size. Instead, feed your snake smaller or medium-sized prey and go for more frequent meals. This is a great tactic if you’ve decided to diversify your snake’s diet, which comes with plenty of benefits in the long run. After all, snakes have a varied diet in the wild because they have freedom of movement and a whole world to explore and hunt in. Such a diet is clearly beneficial, as it provides the reptile with the entire range of nutrients they need to remain healthy.

Risks of Feeding Prey That is Too Large or Too Small

You’ve read that right, there are actually some risks associated with improper prey size.

The main ones to mention include:

Difficulty Swallowing and Digesting

If the prey is too large, your snake may not be able to swallow it properly. This can lead to choking and difficulties with the digestion process.

This is a concerning problem for juvenile snakes, especially due to their need for more frequent nutrient intake. Ideally, they should have smaller, but more frequent meals for optimized nutritional input.

There’s also the risk of regurgitation. Snakes can regurgitate their meals if the prey is either too large or it hasn’t finished digesting the previous meal.

So, you should both avoid oversized prey and adjust the feeding frequency based on your snake’s needs.

As a side note, don’t mistake regurgitation for vomiting. Regurgitation usually occurs soon after ingestion for a variety of causes. These include prey size and stress because snakes require peace and quiet after their meals to digest properly.

You should avoid bothering your snake approximately 2-3 days after its meal.

Vomiting refers to expelling food already digested or in the middle of it. This is usually a sign of illness, but it can also occur due to stress, and it’s more threatening than regurgitation.

That’s because vomiting leads to electrolyte imbalances, which result in dehydration and additional health issues.

Nutritional Imbalances

On the polar opposite, you have undersized prey, often paired with infrequent breeding. If the prey is too small or your snake isn’t eating as frequently as it should, it can experience nutritional problems.

One such issue is calcium deficiency, which reptiles are naturally subjected to.

While optimized nutrition isn’t the only way to prevent calcium deficiency (other factors matter, like genetics and UV lighting), it is a vital one.

You should always adjust your snake’s diet and meal frequency based on its needs.

Health Problems

Aside from nutritional issues and the risk of choking, the risk of injuries and impaction is also worth mentioning. Your snake may be able to swallow the prey and not regurgitate, even if it’s too big, but that still doesn’t make it right.

If the prey is oversized and the snake is hungry enough, it will make an extra effort to swallow it. The result may be impaction, which is an intestinal blockage that can get deadly.

Then you have the risk associated with feeding your snake live large rats. Live prey is preferable because it triggers the snake’s hunting instincts and behaviors, but it’s also risky.

Especially if the feeder animal is large and desperate, as is the case with rats. These can attack and injure your snake in desperation. The snake will still overpower and eat the animal because it’s in its nature to do so.

But the injuries may infect and cause additional problems along the way. Such injuries are especially worrying because they are difficult to detect due to the snake’s position in the tank.

A curled-up snake can hide its injuries by accident, causing them to infect and develop into more severe health issues.

Tips for Choosing and Offering Mice and Rats

How you feed your snake is just as important, or close to it, as what you feed it.

Here are some useful tips in this sense:

  • Be careful with live prey – Snakes will eagerly eat live mice and rats, but this type of feeding comes with its own ups and downs. For one, you have to grow the rats yourself so you have them readily available for your snakes. Then you have the risk of injury that we’ve already discussed. You should always monitor your snake during the eating process to make sure everything goes smoothly.
  • Warm up the prey – No, you shouldn’t warm up the prey by placing it in a microwave. A pan and oil are also out of the question. Instead, place the dead mouse in a plastic bag and submerge the bag in a pot of warm water for several minutes. This will warm up the carcass evenly.
  • Have forceps available – If this is your first time owning a snake, you may have noticed many snake keepers use forceps during feeding time. This is for 2 reasons. First, the forceps allow you to wiggle the prey to gauge the snake’s interest. The second is that using a forceps keeps your hand out of the feeding process. Otherwise, your snake may begin to associate your hand with food. That’s fine with small snakes but not that great in the case of large constrictors.
  • Prepare the meal – This is the more hygienic wording of ‘cut open the rat’s head to expose the brain.’ Doing so leads to a variety of scents that will pique your snake’s interest immediately. I understand if you don’t have the stomach for it, but it’s worth knowing the option is there.
  • Adjust the environmental temperature – Always keep your snake’s enclosure temperature within the ideal recommended gradient. You want your snake to be warm and comfy so that its metabolism will function properly. If the temperatures are too low, your snake won’t eat.
  • Vary the prey’s coloring – Not all rats have the same color. Some snakes are attracted to white and albino rats more, for instance. Adjust to your snake’s preferences and feed it its preferred prey as often as possible.
  • Mind the feeding time – Always feed your snake during its normal hunting hours. In other words, feed diurnal snakes during the day and nocturnal snakes during the nighttime. This may sound like common sense, but common sense isn’t as common as you’d think.

Finally, try different prey items of different sized to see which of them your snake prefers. And don’t attempt to feed your snake if you know shedding is approaching.

The snake won’t eat for some time before and after shedding. Placing a live rat in its enclosure may stress out the snake and the rat, which can end up hurting your reptile.


Snakes are voracious predators that can consume a variety of prey. However, it’s your responsibility to manage the prey’s size and meal frequency, to ensure your snake’s safety and health.

I hope today’s article has set you in the right direction for that.

Robert from ReptileJam

Hey, I'm Robert, and I have a true passion for reptiles that began when I was just 10 years old. My parents bought me my first pet snake as a birthday present, which sparked my interest in learning more about them. read more...