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Why is My Betta Fish Laying at Bottom of the Tank or on its Side?

If you’re used to watching your Betta fish darting around the tank, it can be concerning to see it laying at the bottom of the tank or on its side.

It’s important to check on your fish if you observe this behavior. In some cases, it may be normal behavior such as sleep or rest. However, it can also be a symptom of disease, stress, or an improper environment for your fish.

Let’s take a closer look.

All Possible Reasons to Worry

Let’s peer through the aquarium glass to find out the worrying reasons your Betta laying on the bottom of the tank.

Betta Laying at the Bottom of the Tank
Betta laying at the bottom of the tank

1. Water Temperature is too Low

Bettas are tropical fish that thrive in a warmer tank environment, with an ideal temperature range of 75°F to 82°F (24-28 degrees Celsius) (1). As with most fish, Bettas are ectothermic, meaning their body temperature is regulated by the surrounding water temperature (2).

If the water temperature falls below the ideal range, Betta’s metabolism slows down, and they become less active. This makes them lethargic and causes them to seek refuge at the bottom of the tank to conserve energy and reduce their exposure to stressful environmental factors.

There could be several reasons for a cooler aquarium:

  • If the room temperature is cooler, it makes the tank’s water cooler as well. This is especially true in colder months or if you live in regions with colder climates.
  • Lack of a heater in the tank.
  • Adding cooler water during water changes.
  • Drafts or strong air conditioning in the room.

To fix this issue, you’ll have to warm up the water in the tank. This can be done using an appropriate-sized heater in the tank. Make sure you increase the temperature gradually because sudden increments could shock your fish. Also, make sure you keep the tank away from windows or air vents that could cool it down.

2. Water Temperature is too High

If the tank’s water temperature is too warm, it can lead to lower oxygen levels, which can cause Betta fish to become lethargic and have difficulty breathing. This could be a reason why the fish is laying on the bottom of the tank.

Low dissolved oxygen levels are uncommon, but in summer, if your tank isn’t located in a cool spot, it can easily heat up. To avoid this, monitor the temperature with a thermometer (preferably a digital one) and adjust it in a suitable range using an adjustable heater.

Bubblers can improve oxygen exchange, but they’re usually unnecessary for Bettas as the tank filter already provides enough surface agitation. For 5-gallon tanks, a bubbler isn’t needed but for tanks more than 20 gallons, a bubbler is needed if the filter doesn’t provide enough movement.

3. High Levels of Ammonia, Nitrite and Nitrate in the Tank

All aquarium fish produce ammonia as biological waste. Although Bettas can handle ammonia better than other fish, even low levels of ammonia or nitrite in the water can be harmful to them. To keep your Betta healthy, it’s essential to maintain ammonia and nitrite levels as close to 0 parts per million (ppm) as possible. While a small amount of nitrate is tolerable, anything above 20 ppm can slowly poison your fish.

If the ammonia or nitrite levels in the water rise to 0.25 ppm or higher, it can be highly toxic for Bettas, leading to reduced oxygen-carrying capacity in the blood and causing their gills to turn brown and body colors to turn pale. Betta will exhibit symptoms of alternating between gasping for air at the surface and laying on the bottom of the tank.

Higher levels of nitrate above 40 ppm will weaken the Betta’s immune system and they will become unresponsive, and inactive.

Therefore, it’s crucial to monitor and maintain appropriate levels of ammonia, nitrite, and nitrate in the aquarium. To prevent ammonia poisoning, use a testing kit (preferably API Freshwater Master Testing Kit) to measure the ammonia levels and perform the water changes as needed to keep the ammonia, nitrite, and nitrate levels within the safe range. A tank monitoring system can also help track ammonia levels.

The amount of water changes depends on the tested levels of ammonia and nitrate, as well as the size of the tank. A large, filtered tank should have a 20-30% water change around once a week.

If nitrate levels are consistently high, you may be overfeeding your fish leading to a higher bio-load. Avoid overfeeding and add more plants to bring nitrate levels down.

To keep your Betta healthy, you need good bacteria in the tank. Cycling the tank creates this bacteria, which breaks down harmful substances and keeps ammonia levels within safe levels. But, you still need to change the water regularly to remove waste, restore pH balance, and add vitamins and minerals.

4. Swim Bladder Disease in Betta Fish

Swim Bladder Disease (SBD) is common in Bettas. It can be caused by internal bacterial infection, overfeeding (sometimes Bettas, with their eager appetites, just don’t know when to stop!), bloating, or constipation. Sadly, it’s harder to figure out the exact cause of this disease.

The swim bladder controls buoyancy and helps control the swimming depth in Betta fish. When they suffer from Swim Bladder Disease, they lose their ability to swim properly. They may struggle to hold themselves upright and fall over to their side, get stuck at the surface, or drift to the bottom of the tank.

Betta with Swim Bladder Disease Laying at the Bottom of the Tank
Betta with Swim Bladder Disease laying at the bottom of the tank

Treatment for Swim Bladder Disease includes a diet that’s high in fiber, such as Daphnia. Daphnia acts as a natural laxative and provides the needed nutrition to help your fish recover. The right amount of Daphnia depends on your fish’s size and age, but it’s advised not to feed more than 1.8 grams a day and remove any other uneaten frozen and freeze-dried foods during treatment.

In some cases, Swim Bladder Disease can become chronic and your Betta may need to be euthanized.

5. Stress in Betta Fish

Stress can cause a Betta fish to lay at the bottom of the tank or on its side. Signs of stress include lethargy, loss of appetite, pale colors, and behavioral changes such as hiding or skittishness. Bettas may also clamp their fins to their body in a sign of tension.

Stress can be caused by a number of reasons, such as poor water quality, inadequate tank size, incompatible tank mates, or changes in their environment.

It’s important to note that stress and disease are often linked. Check for signs of stress when your Betta fish shows symptoms of the disease. Even if your fish isn’t sick, take action to identify and eliminate the sources of stress if it’s showing signs of stress.

Adding live plants like Anubias and Java Ferns to the tank can help recreate a natural environment and help reduce stress for your Betta.

6. Illness, Disease, or Parasitic Infection in Betta Fish

Betta fish have weak immune systems that make them susceptible to a range of illnesses, diseases, and parasitic infections such as ich, fin rot, velvet disease, constipation, or Dropsy. These diseases can vary in severity, from constipation which is often easily fixed to Dropsy which is usually fatal. You should know the signs of these diseases that accompany the symptom of laying on the bottom of the tank.

For instance, ich is a parasitic infection that causes white spots on Betta’s body and fins. To cure Ich, you’ve to medicate and cycle the water, as ich contaminates the whole tank.

The primary cause of any disease in Betta is often stress. If you notice any disease symptoms in your Betta, first make sure the water parameters and living environment are optimal and comfortable. As well as treating the disease it’s important to fix the causes of stress.

7. Strong Current in the Tank

Bettas can become stressed and disoriented when exposed to strong currents, causing them to stay at the bottom or sides of the tank.

Bettas aren’t fast swimmers and they prefer calm, slow-moving water. An excess flow from the filtration system can create a strong current that makes it difficult for the Betta fish to swim normally and they become fatigued to go against the flow (3). Strong currents can also make it challenging for Bettas to maintain their position in the water, leaving them vulnerable to injuries from tank decorations or objects.

One way to reduce strong currents is to use a filter that provides gentle flow and allows for the adjustment of the filter outlet and the flow of the aeration device. Another effective method is to use a filter baffle or a piece of foam to create a barrier that disrupts the strong flow of water coming out of the filter.

Baffle the Aquarium Filter
Filter baffle made from a plastic bottle cut into a particular shape

Plants can also be used as they act as a natural buffer to absorb the force of the water. Good plant options include Java Ferns, Java Moss, and Anubias. You can also use tank decorations like flower pots placed in front of the filter to reduce the flow of current.

8. Small Tank Size

While Bettas can survive in tanks as small as 3 gallons, it’s important to remember that size does matter. A larger tank with living plants and hideouts is always better for your fish to thrive.

A smaller tank means less for your Betta to explore and interact with, and fewer hiding places. It’s also harder to maintain optimal water parameters in a smaller tank, as any changes in pH, ammonia, or nitrite levels are dispersed over a smaller area.

A larger environment provides more stimulation for your fish, reducing stress. Larger tanks are also less susceptible to currents caused by filters and air pumps, making it easier for your Betta to swim.

If your Betta is laying on the bottom of the tank or on its side, it may be a sign that it’s time to upgrade to a larger tank with live plants and decorations for your fish to explore.

All Possible Reasons (That You Don’t Need To Worry About)

Although it’s less common, your Betta fish might be laying at the bottom of the tank and be perfectly healthy. Here’s what you don’t need to worry about and how to tell the difference.

9. Old Age

Sadly, most Betta fish have a short lifespan (three to five years). As Betta fish age, it’s natural for them to slow down.

An aging Betta fish will need to rest more, so you might find it laying on leaves or the substrate at the bottom of the tank. As long as other signs of stress and illness aren’t present, then you don’t need to worry – let your Betta fish enjoy its peaceful retirement!

Unfortunately, there comes a time when it’s better for your fish to have a comfortable end of life, so consider euthanizing your Betta if it’s suffering.

10. Resting or Sleeping Betta Fish

Betta fish typically follow human natural rhythms, meaning they sleep at night and are active during the day. Bettas sleep with their eyes open (because they lack eyelids) so it may not always be obvious.

When Bettas sleep, they often find a small space in the tank, rest on the substrate, or sleep on top of leaves. They may appear curled up on one side or even vertically, with their head down. Their color may also change while sleeping. Don’t panic! This is a natural form of self-defense.

If you are unsure if your fish is sleeping, you can gently nudge it to check for movement or turn on the lights to stimulate it. If your Betta is sleeping during the day, it may indicate an unsettling environment at night. Check the light levels and provide a dark space for it to sleep.

11. Betta Fish Taking a Break

Bettas can be lazy and like to take breaks from time to time. This is because swimming with their large fins is hard work. Observe your Betta’s behavior to determine if he is taking a break. Check if his front pelvic fins are still moving or if he is eating and behaving normally. Remember, even fish need a break sometimes.

Wrapping Up

If your Betta is laying at the bottom of the tank or on its side, check its breathing and fins for any damage. If it’s not asleep and doesn’t become lively when woken, it could be a sign of a more serious issue. Familiarize yourself with the signs of constipation, ich, and swim bladder disease, and check the water parameters (ammonia, nitrite, and nitrate), temperature, and pH levels in your tank.

To ensure your Betta thrives, maintain carefully controlled conditions in the tank. There’s little in life that’s as fulfilling as watching your healthy fish dart about and explore their tank – living life to the gills!

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