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Do you have an aggressive turtle that often bites or attacks other turtles in its aquarium? Here’s what’s going on and how you can stop it.

Why Is My Turtle Being Aggressive?

Let’s get straight to the point.

If your turtle is behaving aggressively towards you it is most likely because it is either stressed or afraid. On the other hand, if you have a turtle acting aggressively towards other turtles, it is generally because of one of the following; cramped habitat space, competition over food, or a basking area, a mating ritual, or due to their aggressive nature.

An aggressive turtle will probably try to start a fight with other turtles, like the video below:

In this quick article, I will show you how to identify the reason for your turtle’s aggression, as well as how to reduce or put a stop to it.

Why Does My Turtle Try To Bite Me?

Although some species of turtles are less aggressive than others, just about every turtle will snap at you if it feels threatened.

If your turtle is trying or has bitten you, it was probably because it felt scared.

Turtles tend to bite under these conditions:

  • Reaching your hand or putting your fingers around or close to their mouth in a quick manner.
  • Mistaking your fingers for food during feedings.
  • Being stressed after being moved into a new environment or; being stressed due to improper living conditions.

As long as you avoid the above, you should be safe from being bitten from even the most aggressive turtle species.

You can learn more about this in my article on do red-eared sliders bite.

Why Are Turtles Aggressive (Towards Each Other)?

If you have an aquarium or habitat with multiple turtles and 1 or more of those turtles is acting aggressively towards the others, it is likely due to 1 of the following reasons:

  • Your aquarium or habitat is too small.
  • The turtles are fighting over basking spots or food.
  • The aggression is actually a mating ritual.
  • The turtles are establishing a dominance hierarchy.
  • Inter-species or gender-linked aggression.

I’ll quickly explain how to identify and solve each below.

Aquarium Is Too Small

The very first thing you should check is how much space you have provided for your turtles.

For instance, among red-eared slider owners it is common practice to offer 10 gallons of water for every 1 inch of their turtle’s shell length. And considering that a single red-eared slider can get up to 10 to 12 inches, that’s 100 to 120 gallons of water just for a SINGLE turtle!

When you add another turtle to the mix without also increasing the size of your aquarium, problems start to occur.

In my experience, a lack of space is the most common cause of turtle on turtle aggression in aquariums.

Competition Over Basking Spots And Food

Turtles don’t just get aggressive with each other when there isn’t enough water, they also get fight, nip and attack over basking spots and food.

Competition over basking spots and food is one of the many social behaviors observed by Karen Marie Davis in her doctoral dissertation, Sociality, Cognition, and Social Learning in Turtles (Emydidae).

Typically, this is expressed by the bigger turtles pushing or chasing away smaller turtles for prime basking areas. Ditto for food.

As turtles are opportunistic eaters due to the relative scarcity of proteins in the wild, this type of behavior is largely ingrained in turtles’ instincts.

Mating Rituals

If you don’t know what to look for, you may mistake a mating ritual between a male and female turtle with normal aggression or bullying.

However, very often when a male turtle attempts to mate with a female he IS being aggressive and bullying her.

It’s also quite difficult to know what is normal mating behavior and what is just outright aggression.

For instance, many male turtles will bite a female during courtship, such as:

  • Snapping turtles (Chelydridae)
  • Mud and musk turtles (Kinosternidae)
  • Pond turtles, painted turtles, false map turtles, wood turtles, cooters, and other turtles belonging to the sub-family Emydidae.

Although these bites are often directed at the females’ necks, they are not intended to injure.

This behavior is often followed by fluttering of the male’s two forelegs in front of the female’s head. Check out this video to see exactly what this looks like.

Typically, the best way you can tell this apart is to identify the gender of each turtle involved in any aggression. If it’s a male-female pairing of the same species, it’s probably mating related. If it’s a male-male pairing of the same or different species, it’s probably territorial aggression or a dominance hierarchy.

Dominance Hierarchies

If you have multiple turtles in one aquarium or habitat and you witness aggression between turtles, it may be due to one or some of them trying to establish a dominance hierarchy.

Basically, the males will fight each other in order to establish rank. Males who win more fights are typically higher up in the rank and enjoy greater access to females.

Long ago herpetology experts believed that dominance hierarchies did not exist within turtle populations. However, it has repeatedly been shown to exist. For instance, in an article titled Turtle Mating Systems in the Journal of Heredity, a dominance hierarchy was found in a population of wood turtles. Higher-ranking males within the hierarchy were found to have a larger number of offspring than lower-ranking males.

In some rare occasions, larger turtles have eaten smaller turtles.

Species And Gender-Linked Aggression

Lastly, if the aggression isn’t related to size, basking spots, food, mating, or dominance hierarchies within species, it is probably related to gender or species differences.

Generally speaking, instances of aggression are highest between two males, regardless of species. This often takes the form of bites, gapes, chases, and retreats.

Mating-ritual related aggression between a male and female is next down on the list. Aggression has been noted the least among female-female pairings of the same species.

Basically, what this means it that in general, males can be quite aggressive towards other males (regardless of species) with a serious possibility of injury or harm. Males can also be aggressive towards females (of the same species) with a much smaller possibility of harm or injury. Lastly, females tend to be much less aggressive toward other females.

How Do You Stop A Turtle From Being Aggressive?

If you have a turtle that is being aggressive towards other turtles in your aquarium or habitat, the best, single most effective thing you can do is get a bigger aquarium.

Space matters. And the more you have of it, the less your turtles will feel cramped. The less cramped and “on top” of each other they are, the fewer aggressive interactions will take place.

As a general guideline, I strongly recommend that if you have multiple turtles, get a 100+ gallon aquarium.

Other things you can do to reduce aggression are the following:

  • The more females you have, the less fighting. Two females will be much less likely to bite and snap at each other as opposed to two males.
  • Try not to add a smaller male turtle to your existing aquarium IF it already has a mature male. It is much more likely the bigger male will bully the smaller one.
  • Make sure you have a big enough basking area to accommodate your turtles. If the area is too small, a larger turtle may bully the smaller away from it. In order to do this, you’ll need a bigger UV light.
  • If you notice aggressive behavior during feedings, consider feeding your turtles separately. I often feed my turtles in separate plastic bowls anyway to reduce waste in the water.
  • Own species which tend to be less aggressive than others.

What Are The Most Aggressive Turtle Species?

To be honest, every turtle species can be aggressive under the right circumstances. And every turtle can be docile again, under the right circumstances.

That being said, there are some species which are just naturally more aggressive than others. This list is by no means comprehensive. It’s simply based on my experience and knowledge of different turtles.

Snapping Turtles

Both common snapping and alligator snapping turtles get big, look scary, and are some of the more difficult turtles to take care of.

I would not recommend getting one if you’re new to turtle husbandry. They get enormous so need giant tanks or environments. They are also quite aggressive.

Although both of them are much more aggressive than other species, the common snapping turtle, in particular, is the King of Aggression! This is due to the fact that in the wild it is constantly roaming around rivers, ponds, and lakes for prey. By contrast, the alligator snapping turtle is an ambush predator that lies in wait for passing fish or other prey.

African Helmeted Turtles

Never, ever put more than 1 African Helmeted turtle into an aquarium with another turtle species.

African helmeted turtles are the only species known to hunt in groups. They’ve been known to attack larger prey. Even birds!


Although they look cool, these turtles tend to be much more territorial than other species.

Having a larger aquarium is a must if you want to avoid fights. If you go with a Sideneck, you should check out my African Sideneck turtle food list.

Soft-shell Turtles

Although these turtles are not typically aggressive towards other species, they are much more likely to be aggressive towards their own kind.

They are also more difficult to take care. Be careful when owning more than one.


Yep, sliders! In a study comparing the social behavior of 3 different species of turtle, pond sliders were observed to have shown aggressive behavior much more often than red-bellied and river cooters.

They won’t typically kill another turtle, but they do seem to bite and nip more than many other species.

What Are The Least Aggressive Turtle Species?

Much in the same way, some species of turtle are prone to biting, nipping, and chasing. Some other species certainly feel a lot more “laid-back”.

Diamond Back Terrapins

Diamond back terrapins are known as the “Golden Retrievers” of the pet turtle world for a reason.

They tend to cope with being handled well and generally interact and mix with other species well.

If want to add an additional turtle to your aquarium, I’d recommend looking at these first.

Red-bellied Cooters

In that same study I referenced above, red-bellied cooters were observed to have the least number of aggressive interactions.

Box Turtles

Box turtles in general tend to be more skittish as opposed to aggressive. You can lump Eastern box turtles, Reeves turtles and others in this category.

In my opinion, box turtles are a bit harder to take care of, however, they are much less prone to aggression.


  • If a turtle is behaving aggressively towards you, it is likely because it feels threatened. Back off, and try to avoid quick hand movements before or during handling it.
  • Generally, the most common reason turtles get aggressive with each other is due to a lack of space in their environment.
  • Males tend to be much more aggressive towards other males, regardless of species.
  • If you have a male and female of the same species in the same aquarium, it is likely he will attempt to mate with her. Sometimes this can be aggressive.
  • Female-female pairings or groups tend to be the least aggressive.
  • Turtles can sometimes fight over basking spot access and food. Consider providing a larger basking area and/or feeding them separately.
  • Some species tend to be more aggressive than others, in particular: snapping turtles, African helmeted turtles, snakenecks/sidenecks, soft-shelled turtles and sliders.
  • Some species are less aggressive than others, such as: red-bellied cooters, diamond back terrapins and box turtles.