8 Possible Reasons Your Betta Fish Disappeared (& What To Do About It)

As a teenager, I agreed to fish-sit for my sister-in-law. My job was simple: Feed the fish.

When she came back, she asked where the third fish was.

My jaw dropped. “You had three?”

Even today, I’m called “fish-killer.” But, in fact, betta fish disappear for loads of reasons.

betta fish disappeared atf

#1 Hide and Seek

Don’t underestimate your betta’s ability to find a truly phenomenal hiding spot.

Plant clumps, caves, and other aquarium decor are all potential hiding places.

The most prevalent hiding spot is behind the filter.

If your betta disappeared and reappeared without explanation, this is probably where they staked out.

You might have to take the filter apart to find them.

But oftentimes, this is the kind of fish disappearance where they randomly reappear one day.

It would be cool if they didn’t go into hiding in the first place, of course.

The best way to keep this from happening is to only choose decor with large openings.

Sometimes fish get trapped in hollow decor, and it takes time to get out again.

But if the caves and other decor in the aquarium are more open, the risk diminishes.

#2 Predators

This is not what you meant when you called your betta a snack, I know.

But in truth, there are a lot of risks with giving your betta tank mates. Not the least of which is they may become prey.

Then again, this is not what happens if your betta does not live with any potential predators.

Snails and shrimp are too small to be a danger to the fish.

Yet a goldfish or even another betta could pose a threat if they’re big enough. 

If you have a tank with multiple female betta fish (a sorority), they are likely to attack one another.

Because my sister-in-law’s fish lived with two others, we suspect this is how it disappeared.

We have three tips for prevention in this scenario: 

  • No predatory tank mates
  • Bigger tank
  • Good feeding schedule

When all your fish are satisfied with their environment and their hunger is satiated, odds are good they’ll get along.

But we still don’t recommend keeping your betta with a potential threat.

Some bigger fish are simply temperamental, territorial, or greedy.

These personalities are fun to observe as an aquarist. But your betta could suffer the consequences.

#3 Jumping Out of the Tank

betta jump out of tank

Betta fish are more than capable of jumping out of an uncovered tank.

Not only do you need a tank lid, but you need to keep the water level well below said lid.

Generally speaking, we want to leave a couple of inches of space above the water’s surface.

Most betta owners know to cover their tank, though. Where many people go wrong is by leaving just a small space above the filter. 

You have to understand betta fish are like tiny Olympic athletes. They can jump through the smallest opening if they so choose.

If you have a closed tank with a 1″-inch opening above the filter, fashion a DIY cover.

If you cannot find your betta, step one is to check all around the tank.

While it’s hard on them, some betta fish can survive for a limited time outside of water.

Act fast, and you might save their life. Inspect the area thoroughly, and consider whether other pets might have been nearby.

Unfortunately, many first-time aquarium owners have lost their escaped betta to a cat or dog.

Whether you save this betta or not, consider why they might have jumped out.

But remember, too, they might have just been feeling mischievous or bored.

#4 Low Oxygen in the Tank

Depending on the size of the tank, you might struggle to keep it well-oxygenated.

Some people use an air pump, air stones, or just a strong filter to keep dissolved oxygen levels up.

There are all kinds of aerators out there, and most are pretty easy to set up. 

Lack of oxygen makes your betta feel sick and eventually takes a severe toll on their body.

Your fish should go to the surface for oxygen from time to time.

But if they hang out up there a lot, think about getting them an aerator.

Over time, your betta may become desperate to get more air. This will lead them to jump from the tank if they find even a tiny opening.

#5 Poor Water Conditions

poor water missing betta

Do regular water checks to make sure those water parameters look good.

Water hardness, pH, and temperature all have a huge impact on your betta’s health and comfort.

Any disturbance in water levels throws them off.

Doing frequent tests for water parameters will help you catch the problem before it worsens.

Most issues are resolved just by doing some extra partial water changes. 

Here’s a complete guide to maintaining water quality for your betta.

Sometimes these problems render your fish inactive. But other times they make your fish leap right out of the tank.

#6 Small or Crowded Aquarium

Betta fish need a 5-gallon tank or larger to thrive. This gives them room to be active and allows you to add lots of plants and decor.

Some folks use the tiniest tank for their betta, even going as small as one gallon. 

This is risky for a lot of reasons.

These tanks are more likely to have poor water quality. The bio-load is too heavy for such a small volume of water.

They barely have room for a couple of silk plants and a cave.

Your betta simply won’t be as content to swim around. They’ll get really bored.

Furthermore, using a 1-2 gallon aquarium means struggling with filtration.

Even with a gentle filter, the water current feels strong to your betta in a small space.

In a larger tank, this would not hinder their swimming.

But in a compact tank, they have this water current pushing them, and they struggle to swim.

The problem is only worse in a crowded environment. The bio-load is heavier, and stress is higher.

It’s tough to keep the water parameters in check this way.

But it’s also tough to keep your fish from aggressing against each other.

#7 Behind the Filter

betta hiding not missing

Unfortunately, there is one more way your betta might pull a Steve McQueen. 

Sometimes the filtration system in your tank has a small hole behind it.

Being such little guys, betta fish can wiggle in there and escape the tank.

There’s no great method for preventing this.

Check to see if your tank has an opening like this, and consider fashioning some sort of cover. But this is, of course, a tricky spot to close up.

Say the top of your tank is completely covered, but you do not see your betta anywhere in the tank.

This is the time to check all around the tank. Look on the floor and any rugs or other surfaces nearby.

If you don’t see any sign of them, search the decor more thoroughly and move the substrate around.

When there is any possibility your betta got out of the tank somehow, always start with a search outside of the aquarium.

#8 Buried in the Substrate

Your hidden fish might be tucked in the gravel at the bottom of the aquarium.

This is pretty unusual betta behavior, but it has been known to happen. And it certainly would make you suspect a full-blown fish disappearance!

The truth is, this behavior is way more common in shrimp and snails than in siamese fighting fish.

But if you keep these guys as tank mates to them, your betta might learn a trick or two.

After thoroughly checking the area around the tank and the entire tank, move the substrate around.

It’s harder to see your betta in there if they have a similar color to the gravel or other substrate.

Lots of betta fish keepers have an experience where their fish disappears. But then, days later, there’s an unexpected fish reappearance.

These guys are small and resourceful, so hold out hope.

You might even drop some food in there if your betta can smell it. Be sure to clean it before too long, so you don’t have waste build-up in the tank.

Maybe you know of a specific decoration, plant, or game your betta likes. These are great ways to lure them out.

They may be able to see you, hear you, or even smell changes in the environment.

Missing Fish: Call This Number

Remember, the most common fish hiding spot is the filter. But they may hide in decor, plants, or even the substrate too!

Step one is always to check around the tank in case they jump out. 

If you lost your betta this way, I’m genuinely sorry for your loss.

To lift your spirits, look at these beautiful betta fish colors. Maybe you’ll find your next aquatic friend.

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Jacinta was raised on a dairy farm in Vermont where they worked extensively with cows, chickens, pigs, goats, and other animals. They have a background in writing both creatively and professionally.

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