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Understanding the biology of our fish can be one of the most enjoyable parts of the fish keeping hobby. The more that we have the chance to learn about the denizens of our aquatic tanks, the more that we can better understand and take care of their needs.
Knowing just how large our betta fish grow can help us determine how large of a tank we may need, and help us set a realistic expectation for what our future with these beautiful fish can be.
If you’ve ever asked the question “How big can a betta fish get?” read on for the answer!
Betta Fish Background
Wild betta fish, or Betta splendens are a fascinating animal that has adapted to maximize their survival chances in an oftentimes hazardous environment.
These small creatures often seem especially suited to smaller tanks, but it is best to keep in mind that they still require plenty of room in order to feel safe.
The natural habitat of the betta fish is the warm, tropical waters of Southeast Asia, specifically around the areas of Thailand, Cambodia, and Vietnam (hence the moniker siamese fighting fish).
These areas are prone to periods of drought, and as such this ingenious little fish has adapted a specialized tissue system known as the labyrinth organ.
These enable the fish to breathe surface air, meaning that they can survive for periods of up to 6-8 hours on dry land while hopping between shallow bodies of water.
How Big Do Betta Fish Get In The Wild?
Unlike species like the goldfish, which can reach incredible sizes of upwards of 18.7 inches in length, betta fish tend to stay on the smaller size, both captive and in the wild.
Wild betta fish are known to reach sizes of between 2.5 and 3 inches in length maximum. These small and colorful species of fish are better adapted to relatively small areas such as rice paddies and small ponds, places where a larger fish would surely begin to feel cramped for space.
This does not mean that they do not need their proper amount of space, quite the contrary. Male bettas especially will vie for territory, putting on elaborate defensive displays and even fighting off other fish for an adequate amount of room.
How Big Can A Betta Fish Get?
Generally speaking, betta fish are a relatively small breed, suited to a small tank of 3 gallons or more. It’s not uncommon to see your betta grow to the size of 2.5-3” in length over the course of its life, but one should not expect them to grow much larger than this unless it’s the betta anabantoids, also known as the giant betta fish.
How Big Can A Male Betta Fish Get?
Including the fins, male bettas get to an average length of 2.5-3” at their full size. Some bettas may be slightly smaller due to differences in diet or breeding, but they will tend to stop growing upon reaching this size.
Adult male betta fish usually have larger fins than a female betta, and come in more exciting, vibrant colors.
How Big Can A Female Betta Fish Get?
Male and female bettas reach the same size of 3 inches long at their maximum growth. Female betta fish will tend to have slightly smaller fins than the males, but this doesn’t mean that male betta fish grow bigger.
Additionally, females tend to be more dull in appearance and color than their male counterparts, as they do not use display-based tactics to gain territory.
For those interested in breeding, baby bettas begin at about 0.3 inches long as eggs, then will hatch and reach around 1.9 inches of growth over the first 11 weeks of life. After seven months, baby betta fish will reach their adult size of 2-3 inches in length, and will cease to grow larger.
Do Betta Fish Grow To The Size Of Their Tank?
A common misconception about betta fish (and many other species such as goldfish, for that matter) is that betta fish growth is dependent upon the size of their tank.
As you may be able to tell based on the previous information, while minimum betta fish tank size is very important, bettas are limited in how much they can grow more by the genetic capacity that they have for growth than by the environment around them.
Feeding your betta a balanced diet high in proteins and essential amino acids is the best way to help them grow, rather than simply buying a new tank. The food that your betta fish eat is an integral part of how healthy they are.
If betta fish were simply able to grow to the size of wherever they lived, we’d be hearing more stories of fully grown betta fish reaching enormous sizes in the tropics where they originate! Likewise, we’d see our fish never stop growing as we buy larger tanks over time.
How Large Of A Betta Tank Do I Need?
While some pet stores may try to sell you on the idea that your tank can be a tiny bowl of no more than 1 gallon, this is a surefire way to set them up for health complications and even premature death.
You may have even seen a local pet store where betta fish come in containers as tiny as small cups. This does not mean that this is enough space for these fish to thrive!
The reason for this is that in small fish tanks without much water flow or proper filtration, fish wastes, leftover food, decaying matter and other toxins can quickly accumulate. This leads to a massive spike in the ammonia content of the tank, meaning that toxic shock can be imminent.
This causes your betta to have a reduced immune response, along with damaging their sensitive gills which can lead to death.
Minimum Tank Size
At a minimum, I recommend at least a five gallon aquarium for a single betta fish. When considering having multiple bettas or a community of other fish, a bigger tank is necessary to prevent nipped fins and constant battling.
My article “How Many Guppies In A 5-Gallon Tank?” might help you figure out what kind of tank size you need.
For a single male with peaceful neighbors such as mystery snails and plecos, a 5-10 gallon size tank can work just fine. For a tank with a male and female, or one with a “sorority” of multiple female bettas, consider a tank of between 10-15 gallons with lots of hiding places as a good starter. Check out this review of small fish tank stands, you might need it later.
Can A Tank Be Too Big For A Betta?
In general, the answer to this is no. Assuming that all of the normal considerations for tank set up are done adequately (water quality, water temperature, filtration, etc,) a larger tank should simply make your betta fish happier.
Having an aquarium with plants such as java ferns and anubias can not only provide food for your omnivores and herbivores to eat, but gives your bettas a place to hide and destress.
Having more territory to claim, plants to hide behind, and room to explore is exactly what betta fish live for.
Providing an aquarium with substrate, live or fake plants and more space to hide and decorations to break the line of sight is a great way to help your betta fish reach their full potential while lowering stress.
What Is The Best Tank Size For Betta Fish?
For a single betta, a minimum of 5 gallons should be adequate. When looking to add a variety of species, or more than one betta fish, consider tanks of 10-15 gallons as a good starting place.
Keep in mind that having multiple males will cause territorial disputes and fighting over food, leading to nipped fins and potentially even death for one of them.
Mixing a male with multiple females can work, and this setup allows the male to distribute his attention to more than one female, saving an individual from extra harassment.
Helping Your Betta Reach Its Maximum Potential
While there is no surefire way to ensure that your fish will grow to a certain length, there are some good practices when it comes to what we feed and how we set up our tanks that can keep them healthy and strong throughout the betta’s lifespan.
A relatively neutral pH of 6.5-8 works best for bettas. They are a hardy fish and capable of handling levels outside of this range, but they thrive best in a more neutral and healthy environment. And remember that they are still susceptible to common aquatic diseases even if they are generally hardy.
Bettas do best with a temperature between 75 and 80 degrees Fahrenheit.
Bettas are carnivores, and require a balanced diet full of vitamin and mineral-rich foods. Feeding them a mix of pellets/flakes that are specifically formulated for them, along with live foods and things like freeze dried bloodworms and brine shrimp as a supplement can be a great way to vary their diet.
When establishing a diet for the fish in your tank, I recommend consulting with a trained veterinarian or aquarist to ensure that all of their needs are properly met.
As a side note, if you decide to simply feed them more food this will not likely make the betta fish grow any faster. Overfeeding can lead to betta fish suddenly not eating and serious health complications such as bloat and stomach problems, so stick to your set betta feeding schedule for best results.
Throughout today’s article, we looked at how big can a betta fish get, both in the wild and in captivity, along with some helpful tips for getting them to reach their maximum size.
In general, bettas get to around 2.5-3” in length at full adulthood, and will stay the same size for the rest of their lives.
Providing clean water, adequate tank parameters, and a balanced diet are by far the best ways to maintain the overall health required for bettas to reach their largest potential size. Always keep in mind that a healthy environment equals healthy fish.
Feel Free To Share!
As always, thank you for taking the time to read today’s post on betta fish care. For another interesting read, find out if betta fish can see in the dark or this review about filters for small tanks.
Feel free to share this information with any other betta fish fanatics you may know, and I wish you the best of luck on your continued aquarium adventures!