When starting your first turtle tank, it is typically recommended you start with one turtle. However, once your tank is up and running, it’s only natural to want to find your turtle a friend. After all, adding another animal to your tank will give your turtle company and make your tank more exciting to watch.
However, playing match-maker with turtles is not as easy as it sounds. When choosing a new tank inhabitant, you must consider the biology, personality, and environmental requirements of both your turtle and the companion you are considering.
Can You Put Fish in Your Turtle Tank?
The short answer is yes. You can put fish in your turtle tank. Fish and turtles can live together harmoniously, as long as you choose the correct fish, turtle, and environment. Below, we will go into detail about what to consider, and introduce some of the species that work best in turtle habitats.
Things to Consider When Choosing a Companion for Your Turtle
1. Species of Turtle
Most turtles are omnivorous, which means they eat both plants and animals. To put it simply, if they catch your fish, most turtles will eat your fish.
However, you can minimize this risk through timing and your choice of turtle. The easiest way to protect your fish from turtle predation is to only add it to the tank once your turtle has matured. Most turtles are more carnivorous when they are juveniles, and switch to a near-vegetarian diet as adults. Therefore, adult turtles will be far less likely to eat your fish.
If you haven’t yet chosen a turtle, you can also choose a species of turtle that is less likely to hunt the fish. Species like Mud and Musk turtles are not only terrible at hunting; they also have no interest in it. However, many of the more active turtles, such as Red-eared Sliders, Painted Turtles, and Cooter Turtles, will enjoy the challenge of the hunt.
2. Species of Fish
When choosing a fish for your turtle aquarium, you want to choose a species that is less likely to be eaten. To do that, you can go one of two routes.
Your first option is to choose a fish species that is too big or too difficult to eat. Your second option is to choose a fish that is too quick and too feisty for your turtle to catch. Below, we discuss some of the most popular fish companions for turtles, as well as some of the fish you will want to avoid.
3. Aquarium Size
If you are adding new animals to the aquarium, it is important to ensure that you have enough room for them to have their own area in the tank. If your tank is too small, you are much more likely to have aggressive encounters between your tank inhabitants.
As a rule of thumb, your aquarium should be at least 80 gallons if you are adding any animal to your turtle tank. If you would like to be more precise, you can calculate the habitat requirements for each species.
Turtles require 10 gallons of water per inch of shell length, while most fish require at least a gallon of water per inch of fish length. When making your calculations, make sure you are using each animal’s full-grown size to account for any growth.
4. Tank Conditions
It is important to make sure that your tank inhabitants prefer the same environmental conditions, including temperature and water quality. If your tank inhabitants belong in different environments, they can experience stress, illness, or even death.
Most turtles require a water temperature range of 72-800 Fahrenheit (F). This temperature range is far warmer than many freshwater fish prefer.
Water quality is also extremely challenging when mixing turtles and fish. Turtles have an exceptional bioload, due to their frequent expulsions and messy eating habits. While turtles are relatively hardy and able to thrive in the varying water conditions due to their behaviors, most fish are not.
If you choose to add fish to your turtle tank, you will need a filter that can accommodate the bioload of both your turtle and your fish. It is also best to get a fish species that can thrive in an environment with varying water quality.
5. Hiding Spaces
Before adding fish to a turtle tank, it is important to ensure that you have decorations to help ease the transition for both the turtle and the fish. Consider adding decorations or plants that can break lines of sight within the tank. This will help de-escalate tense situations and give the tank inhabitants a feeling of privacy when needed.
If you are putting smaller fish in your tank, it can also be beneficial to have areas that your fish can access, but your turtle cannot. Especially if you have a turtle that enjoys chasing the fish, giving the fish an area where they can relax will be essential for their overall health. Items like PVC pipes offer great safety areas for small fish.
Top 6 Turtle Companions
Below, we have outlined the top 6 companions for turtles. While this is not an exhaustive list, the species below have all proven their ability to interact with most, if not all, freshwater turtles.
1. Tetra Fish
Tetra fish are one of the most popular groups of freshwater fish. Tetra fish are small, brightly colored, energetic fish that typically enjoy living in small schools. Like turtles, they prefer temperatures of 75-80o F and are relatively resilient to water quality changes.
Tetras are a fantastic choice as a turtle companion, especially when introducing a fish species for the first time because they are cheap to purchase and typically too fast and intelligent for a turtle to catch. However, most tetra species are schoolers, so be prepared to add more than one fish to your aquarium.
Zebrafish, also known as Zebra Danios, are another small fish that can do well with turtles. Like Tetras, Zebrafish are quick and boisterous fish that can successfully evade (and sometimes even playfully taunt) your turtle. They are a schooling fish and will do best when added in groups of 6-7 individuals.
Though Zebrafish prefer temperatures of 65-77o F, they are comfortable in a wide range of temperatures and can thrive in the warmer turtle habitat. Zebrafish are tough fish that not only survive but thrive in a wide range of water qualities.
3. Suckermouth Catfish (Common Plecostomus)
Suckermouth Catfish, also known as Plecostomus, are one of the easiest species to keep with turtles and one of our personal favorites. Suckermouth Catfish prefer water that is 72-86o F, but they can thrive in nearly any environment.
Suckermouth Catfish grow up to 20 inches in length and are protected by armor-like scutes that cover their upper body and head. As a result, Suckermouth Catfish are generally too large to eat, and robust enough to hold their own in a turtle environment. However, their size also means that you will need a larger tank to accommodate them.
Most importantly, Suckermouth Catfish are algae eaters. They will eat the algae off of your tank, decorations, and, most importantly, your turtle! Suckermouth Catfish will help keep your turtle’s shell and exposed skin free of any algae, microorganisms, and bacteria, and save you time on maintenance.
4. Pictus Catfish
Pictus Catfish, also known as Angel Cats, are white and black catfish with giant barbels and bubbly personalities. Pictus Catfish are quick swimmers that reach sizes of 5 inches in length, making them quick and large enough to coexist with turtles comfortably.
Pictus Catfish have sharp spines along their fins, so be careful when adding them to your tank. Though these spines have the potential to cut your turtle’s soft skin, only one poke will be enough to teach your turtle to keep his space. Of all the fish on this list, the Pictus Catfish is the best for juvenile turtles that enjoy hunting fish.
5. Koi Fish
Koi are a great option for turtles kept in outdoor, larger ponds. Koi are a very peaceful species of carp that can grow up to 36″ in length. Though baby koi may be eaten by turtles, juveniles and adults are far too large to be mistaken as food.
Due to their size and space requirements, koi should not be added to smaller, indoor aquarium habitats. However, if you have a space large enough to accommodate them, koi will happily coexist with most turtle species.
6. Other Turtles
A turtle of the same or different species can also make a great companion for your turtle. However, new turtles must be added under the right conditions to mitigate aggressive behavior.
Whenever you have multiple turtles, there is a chance for fighting to lead to injury, maiming, or death. To avoid these situations, make sure any turtle you add meets the following requirements:
- Turtles in the same tank should be roughly the same age and size. If adults are mixed with hatchlings, the adults might eat the babies. Likewise, large, adult turtles may bully smaller, juvenile turtles.
- Make sure you have enough water and basking areas for all turtles. Most aggressive altercations result from limited resources within the tank.
- If you have three or more turtles from the same species, make sure your ratio favors female turtles. In situations where there are more males than females, males will often fight.
- If you are introducing a new species, make sure the two species can coexist. For example, snapping turtles and softshell turtles are territorial, and should always be housed singly.
Turtle Companions to Avoid
As with any species, there are certain fish that turtles simply do not get along with. When choosing a fish for your turtle habitat, it is best to avoid fish with the following characteristics:
- Fish that are too aggressive or can injure, maim, or kill your turtle. Example species include large catfish, piranhas, electric eels, lobsters, and Oscars.
- Fish with long, flowing fins. Long fins make the fish more noticeable to a turtle, and make it harder for the fish to escape a turtle’s bite.
In addition to fish that fit these characteristics, there are two specific species that should be avoided when choosing a turtle companion, even though they are frequently recommended at pet stores:
Goldfish are one of the most common fish recommended for turtle tanks, yet they are fraught with challenges. As we mentioned above, when choosing a companion, aquarium size and tank conditions are two of the most important factors to consider. However, when analyzed for goldfish, both of these factors fall short:
- Aquarium Size: Goldfish are known as indeterminate growers, meaning they never stop growing. This, combined with their long lifespans (10-15 years) and high reproductive rate, allows them to quickly overwhelm a tank. Unless you are accounting for numerous 12-inch goldfish when you buy your tank, your turtle and goldfish will quickly find themselves short on space.
- Tank Conditions: If turtles have one of the worst bioloads in the freshwater aquarium field, then goldfish are the turtles of fish. Like turtles, goldfish have bioloads that far exceed their size. Unless you have a powerful filtration system and are willing to put in longer maintenance hours, your turtles and goldfish will combine to produce levels of ammonia that are unhealthy for all species involved.
Additionally, goldfish are cold-water fish that prefer maximum temperatures of 74o F. In a tank with goldfish and turtles, you are then required to either make the water too warm for your fish or too cold for your turtle. Either way, you end up stressing one of your tank inhabitants.
Therefore, while goldfish are fun, beautiful fish, their addition in turtle tanks adds unnecessary stress to both the turtle and the goldfish.
2. Betta Fish
Betta Fish are typically housed singly due to their aggressive natures. This independent streak, combined with their gorgeous colors, can make them seem like the perfect turtle companion. They are not.
When housed with turtles, Betta Fish quickly reflect the nature of their names. With their bright colors, long, flowing fins, and relatively slow demeanors, Betta Fish are easy bait for hungry turtles.
For the safety and longevity of your Betta, do not house them with a turtle.
How to Introduce Fish to Your Turtle Tank
As with any new aquarium addition, how you add a new inhabitant can greatly influence the success of the addition. Once you choose a new edition for your tank, follow these steps to maximize your chances of a successful move-in day:
Feed Your Turtle Before the Introduction
A full, content turtle is far less likely to associate your fish with a dinner bell.
Acclimate the Fish to the Water
Whenever you add a fish to a new environment, it is important to acclimate them to the new water temperature and conditions by following these steps:
- Float the sealed bag that your fish is in on the top of the water in your turtle tank for 10 minutes.
- Open the bag and add one cup of aquarium water, then reseal and allow the bag to sit for another 10 minutes.
- Repeat the previous step until the floating bag is approximately half aquarium water and half original water.
- Use a net to transfer the fish into the tank. Make sure you don’t transfer any of the water from the bag.
Monitor the Reactions of Your Fish and Turtle
The initial reactions of your fish and turtle will give you insight into how they will interact long term. If your turtle nips at the fish repeatedly or bothers it incessantly, you should remove the fish and house it elsewhere or return it to the store. If they appear to tolerate one another, continue to monitor the turtle and fish for the next several days to ensure that aggressive behaviors do not develop.
Most Common Turtle Companion Mishaps
No matter how much research you do, there is no guarantee that your turtle will like their new companion. However, avoiding the most common mishaps can certainly improve your odds:
- Don’t choose fish that the turtles see as easy, obvious prey.
- Don’t choose fish that require environmental conditions different from your turtle.
- Don’t add companion species if your turtle is territorial.
- Keep your turtles well fed.
Turtles are complex creatures with unique personalities and preferences. However, if you do your research and monitor your turtle’s behavior, you can find them a lifelong friend.