How Old Is My Betta Fish: 6 Markers Determining Species Age

how old is my betta
Japanese Fighting Fish is reader-supported. When you purchase through one of our links we may earn an affiliate commission (at no extra cost to you).

Last Updated: July 28, 2022 by Flora Gibbins

If you want to know how old your betta fish is, it means that you either bought a new betta or want to figure out whether it’s sick or simply aging. In either case, it’s very important for you to estimate the age of your betta to maintain it properly.

Not to mention, you don’t want to buy a betta that’s too old, or else your fish tank will just be its near-future graveyard.

In this guide, we’ll help you get a rough estimate of how old your betta is.

1. Size

Betta Growth Chart

Measuring your betta’s size is the easiest way to tell its age. A healthy adult betta should measure around 2 inches in length.

It can be tricky to measure the length of your betta since you can’t just take it out of the aquarium and stick a measuring tape on its back.

The simplest method to measure the length of your betta is to grab a measuring tape and wait for it to get as close as possible to the wall of the aquarium. Then, hold the tape against the outer wall and check the length of your betta.

On a side note, keep in mind that young bettas stop growing in size a few months after they hatch. So it can be hard to judge how old a betta fish is based on size only.

2. Stripes

Breeding stripes

Stripped bettas are young. Any visible horizontal stripes on your betta’s body mean that it’s younger than 2 months, and its color hasn’t fully developed yet. Wild betta fish use these stripes as a natural camouflage to blend into the surrounding environment and protect themselves from predators.

Just because there are stripes on your betta’s body doesn’t mean it has to be related to age. 

Extreme stress may cause these stripes to appear on your betta’s fins and back. So, if your betta develops stripes out of nowhere, they’re most likely related to stress.

There’s another type of stripe that may appear on your betta’s body during mating season. But unlike age-related and stress-induced ones, the stripes that signal your betta wants to mate are vertical.

3. Scales and Fins

Aging Betta Fish

Healthy adult bettas have long fins, while younger bettas have tiny ones.

If your betta has beautiful flowing fins that look nice when swimming, it’s a good sign that it’s young and healthy. However, seeing tiny tears on your fish’s flowing fins shows that it’s reached old age already.

On the other hand, a betta that’s too young will have tiny fins. In that case, it’s either a juvenile or a baby. It’s also worth pointing out that female bettas often have shorter fins than males.

4. Eyes


Bettas can see quite well. Your betta’s eyes aren’t that different from humans; they’re quite aware of everything happening around them. They can even distinguish between different colors and notice when you throw them some food.

However, older betta fish are at a higher risk of contracting eye infections. The most common sign of eye infection is the formation of cataracts over your betta’s eyes that impact their eyesight. They also make their eyes appear cloudy.

If you notice that your aging betta can’t see properly, then it’s probably at least 1.5 years old. But don’t worry, bettas with poor eyesight can still live for years if you manage to feed them properly.

However, we’d recommend keeping tankmates away from older bettas with damaged eyesight, just to make sure that they don’t hurt them.

5. Back


Old bettas often have a hunched back. It can either be a slight curvature or a prominent one. Typically, the back of a betta starts hunching once it hits the one-year mark. But the good news is that it’s not something to worry about. Your betta can live with a hunched back for years.

However, you might want to consider making a few adjustments to the fish tank. For example, you can add some resting areas in the aquarium, especially near the surface of the water. This allows your old bettas to swim freely without exerting too much effort, which naturally leads to lower stress levels.

Additionally, make sure that you inspect your betta’s tank and remove any sharp corners or objects you counter to protect your fish from getting hurt.

6. Lethargy


Just like how aging humans are more lethargic than youthful ones, older bettas tend to be less active than younger ones. Old bettas swim sluggishly and spend most of their time at the bottom of the tank. As your betta ages, it’ll start sleeping much more frequently than younger bettas.

In contrast, you’ll notice that a healthy adult betta likes to explore the environment around it and make nests frequently.

There’s one thing to keep in mind, though: younger bettas aren’t supposed to swim slowly. If you have a very small betta and you notice that it’s lethargic, it probably means that it’s very sick. Look for other signs of illnesses such as cloudy eyes, color fading torn or dark fins, and a gold sheen.

Tips to Make Your Betta Fish Live Longer

If you want to keep your cute little betta for as long as possible, you need to take good care of it from the moment you come home from the pet store. Here are some tips to extend the lifespan of your aging betta fish:

Keep It an Adequately-Sized Aquarium

Typically, you should keep your betta in tanks larger than 5 gallons.

Pet stores keep young bettas in cups or plastic bags to sell them, but that doesn’t mean they’re intended as long-term habitats for healthy fish.

Wild bettas live in shallow waters, but that doesn’t mean it’s OK to keep them in small aquariums. Of course, including tankmates in the aquarium mean you’ll need a large tank to accommodate your fish community.

Keep Male Bettas in Separate Tanks

Male bettas are quite terrortoiral. So keeping a group of male bettas in the same aquarium isn’t a good idea. Bettas are actually known as Siamese fighting fish. They were used as a source of entertainment, where two bettas are put in the same tank to fight.

Wild male bettas fight for space, but in their natural habitat, bettas can simply escape if they’re losing the fight. In captivity, things get trickier because they’re kept in a very small space. So they’ll keep fighting for their lives until some or all of them die.

To extend the life of male bettas, keep them in separate tanks. 

And if you don’t want to maintain a whole aquarium for a single male betta, consider adding tankmates from other compatible species, such as loaches, snails, and rasboras.

Feed Them a Well-Balanced Diet

Bettas are carnivores, and luckily, they’re not picky when it comes to food choices. If you want your older betta to live a happy, long life, feeding it a balanced diet is key.

Old bettas require a high amount of protein and fat. Brine shrimp and blood worms are some good options for adult bettas. Flake or frozen food should get the job done, but make sure that they’re specifically intended for betta consumption.

Even if you never cared for your betta’s diet throughout its whole life, it’s never too late to make healthy adjustments to its food sources.

Install a Heater and Filter

Equipping your fish tank with a heater and filter can do wonders when it comes to the health of aging betta fish. As your betta ages, it becomes less tolerant of cold water, especially since they live in warm waters in their natural habitat.

In addition, filters keep the water in the tank suitable for your old bettas to thrive.

Watch This!

Frequently Asked Questions

How old are bettas when they’re sold?

Most fish store owners offer male betta fish for sale when they’re over a year old. However, female bettas are often sold at a younger age, usually when they’re 6-months old. The reason is that male betta fish take more time to mature.

How long do betta fish live?

If you take proper care of your betta fish, it’ll live up to 5 years from the moment you bring your betta home from the pet store. However, many bettas die at a relatively younger age. As a general rule of thumb, bettas can survive 2-5 years in captivity, depending on how well you maintain them.

How do I know that my betta fish is aging?

Here are some of the most common signs that your betta fish is getting older:

  • Fading colors
  • Too many naps
  • Torn fins
  • Weight loss
  • A white dot on its head
  • Lower appetite
  • Fewer or no bubble nests
  • Slower reactions


To recap, telling the exact age of a betta can be challenging unless it’s a baby. Still, you can get a very close estimate of the age of normal adult bettas by checking a few factors like size, eye dullness, color, and back shape.

For younger bettas, transparent fins and a very small length (half an inch or shorter) mean that the betta is only a few weeks old.

About The Author

Leave a Comment

Your email address will not be published. Required fields are marked *