Why is my betta fish lethargic?

In this article, we will answer the question “Why is my betta fish lethargic?”. We will also discuss possible causes and illnesses that could cause lethargy.

Why is my betta fish lethargic?

If this happens within the first few days of getting the betta, the water quality is the most likely culprit. Other substances could be to blame, but if frequent water changes don’t solve the problem, more investigation is required. Test the pH of the water – bettas thrive in water with a low to neutral pH, so if yours is too high, that could be the issue.

Possible causes of lethargy

Understanding your Betta fish’s behaviour may assist you in determining when action is required. Betta fish resting towards the bottom of the tank can be caused by a variety of factors, some of which are as follows:

Your betta fish is getting old

Bettas have a short life expectancy. These fish may survive for three to five years in ideal conditions! If you’ve had your Betta for a long time, it may be showing signs of old age. Bettas, like any other animal, see a decline in performance as they get older. 

In order to speed up their surroundings, they just don’t have the same level of energy that they did when they were younger. Their bodies begin to slow down, and they struggle to keep up with younger fish. 

As a result, the majority of older fish choose to take a little additional time to unwind and rest. Your fish may begin to lay down on leaves or spend more time resting on the tank’s bottom substrate.

Ammonia poisoning

Your fish’s excrement will cause ammonia levels in the tank to rise, which will harm your fish. Ammonia is a poisonous toxin for fish, as you undoubtedly know. It can inflict chemical burns on the gills, which can result in death. 

When it comes to ammonia, the problem is that it is undetectable. To keep these levels from soaring, you’ll need to rely on regular tank maintenance and monitoring. For better or worse, regular water changes and a high-quality filtration system are required. 

Without a suitable filter in place, ammonia levels will continue to build in your water supply. Your Betta fish will become weaker as a result of this. They’re having trouble breathing. 

Ammonia problems are also common in small tanks or surroundings that are overcrowded. Check ammonia levels with a testing kit. 0 ppm is the only amount that is considered safe. If you raise the temperature over that, your fish may suffer.

The current is too strong

Strong currents are not good for betta fish. In actuality, their colossal fans are just decorative. They aren’t doing much to assist this fish in swimming. Your fish may get exhausted if there is a lot of flow coming from the filter or an air pump. 

Fighting a strong current all the time takes a lot of energy. Your Betta fish may have had enough and decided to retire to the tank’s bottom. 

In order to limit the quantity of water that passes through your filter, you might employ a sponge filter. You might even direct the current toward plants or decorations. Breaking up the current will help to lessen flow in the aquarium significantly.

Nitrate poisoning

Another chemical produced by fish faeces is nitrate. It’s a by-product of bacterial degradation, though. Ammonia is converted to nitrites by bacteria in a well-cycled tank. The nitrites will next be broken down into nitrates. Nitrates, on the other hand, are less toxic than ammonia. They still cause a lot of damage, though. To make matters worse, nitrate is a toxin that takes time to kill.

It causes the fish to become drowsy and feeble (and might cause them to lay at the bottom of the tank). Your Betta may lose its appetite and have trouble breathing. You could even detect a difference in the colour of their skin. Check the nitrate levels in your water using your water test equipment. You shouldn’t have more than 5 to 10 parts per million (ppm) of lead in your system.

The water is too hot

Bettas are vulnerable to temperature shock. Warmer temperatures are preferred by these fish. However, excessive heat throughout the summer can cause a variety of health issues. 

Warm seas, on the other hand, release oxygen far more quickly than chilly waters. The issue isn’t so much with the temperature. Your fish, on the other hand, is suffering from a shortage of oxygen.

If there isn’t enough oxygen in the tank, your Betta fish will be gasping for breath near the bottom of the tank. Water without a strong supply of oxygen is a severe concern, even if it can breathe atmospheric air.

Swim bladder disease

The swim bladder of your fish is a very important organ for swimming. It is in charge of regulating buoyancy. Swim bladder illness is characterized by a fish swimming in strange patterns, having difficulty moving, or lying at the bottom of the aquarium.

A high prevalence of this ailment is found in betta fish. In addition, these fish have ravenous appetites, and as a result, they usually devour far more food than is recommended for them. Constipation and issues with the swim bladder might result as a result of this.

High-fibre foods like Daphnia and blanched peas can be used to treat the condition. Reduce the amount of food you provide in order to avoid this happening again in the future. Swim bladder illness can be persistent in some cases. Not all fish respond to treatment. Fish must usually be euthanized in these situations.

Other diseases

Your betta fish may be sick if they’re acting sluggish and laying near the bottom of the tank. 

Bettas are susceptible to a variety of illnesses. Because of their compromised immune systems, these fish are more susceptible to illness than most other species. Betta fish can become weak due to diseases such as Ich, Bloat, Dropsy, and others. 

Your betta fish will get anxious and more susceptible to sickness if things go beyond the recommended range.

Just relaxing

The presence of a Betta fish near the bottom of the tank isn’t usually a reason for alarm. Sometimes all your fish wants to do is chill out. Take a look at the way they carry themselves about. If the pelvic fins are still moving, it’s possible that your fish is simply resting. They may move around a little bit before settling down on the substrate.

While their massive fins are impressive, they can be exhausting for a Betta. Consequently, they may need to take a break. This is completely normal, and there is no cause to be concerned about it at this time.

The water is too cold

Cold waters that are beyond the Betta’s comfort zone, like excessive heat, can cause problems. The water temperature in your tank should be no lower than 74 degrees Fahrenheit in ideal circumstances. 

If the temperature goes below this level, the metabolism of your fish will slow down. Oxygen absorbs at a slower rate as well. Your fish will become quite feeble and lethargic as a result of this chain of events. 

If temperatures aren’t raised, your fish may become stressed and contract a sickness.

The tank is too small

Many new fish owners believe that Bettas can live in any environment. True, they may live happily in aquariums as small as three gallons. 

Your fish will be bored if they are confined to a small barren area. There isn’t much to discover. Your Betta fish will quickly lose interest in things, leaving them with little choice but to lie at the bottom of the tank. 

Allow your Betta fish to have more space to explore. Consider increasing the tank’s capacity by a few gallons. You should also provide your fish with a variety of enrichment materials. Caves, flora, and natural embellishments are examples of this. All of these factors will contribute to the overall enjoyment and health of your fish.

Sleeping is a must

Betta fish, believe it or not, have the same needs as any other animal when it comes to sleep. They sleep in the same basic pattern as humans. They prefer to sleep throughout the night and be active during the day. The possibility exists that they will be found dozing towards the bottom of the tank if they do not receive enough sleep at night.

Bettas have a distinct reputation for resting in strange places, which has earned them their title. They can sleep on top of plant leaves, cuddle up in nooks, or relax on the substrate. 

Consider your nighttime arrangement if you see your Betta napping a lot throughout the day. Allow your fish to sleep in a dark, calm area at night to ensure they get the rest they require.


In this article, we answered the question “Why is my betta fish lethargic?”. We also discussed possible causes and illnesses that could cause lethargy.

If you have any questions or concerns, please let us know in the comments section below!

Frequently Asked Questions (FAQs): Why is my betta fish lethargic?

What are the signals that your betta fish is near death? 

Discolouration along the body of the betta fish, such as white or brown spots, are also indicators that the fish is soon to die. Swimmers who exhibit unusual swimming patterns or whose fins are shortened or degrading may be suffering from a serious illness.

Why is my betta fish sluggish and refusing to eat? 

When the temperature in the tank rises over a certain level, you may notice that the betta fish stops feeding. In addition, because Bettas are cold-blooded, they get a significant portion of their energy from the temperature of their surroundings. If you keep your betta in a tank that isn’t warm enough, it will become lethargic and have a sluggish metabolism. 

Why hasn’t my betta been active in the recent past? 

It might be a result of insufficient diet, sickness, or poor water quality in the tank. It could also be because your Betta is getting older and its life is ebbing away from its body. Similarly to humans, elderly Betta fish would be more sluggish and inactive than their younger counterparts.

Is it possible that my betta fish is sick or old? 

It could be an indication of sickness if your betta gets lethargic or loses colour over a few days or weeks. If the symptoms appear to be coming on gradually and your attempts to treat them seem futile, it’s possible that your betta is getting old. 

Is my betta fish dead or sleeping? 

Simply simple, dead fish do not breathe. Examine your betta’s mouth and gills closely. Even when your betta is sleeping, it should be drawing water into its mouth and exhaling it through its gills to keep itself hydrated. Speaking of which, your betta’s mouth and gill movement will be significantly slower while it is sleeping than while it is awake. 

Is it feasible to save a betta fish that is dying?

Your Betta Fish, on the other hand, can live for up to six years if properly cared for. If you believe your Betta Fish is dying, there are several options for treating and reviving it. Rather than giving up, honour their name by trying to keep them alive.


Common Betta Fish Disease Symptoms for Sick, Lethargic & Clamped Fins. https://japanesefightingfish.org/common-betta-fish-disease-symptoms/

Yang, A. 2021. Why Your Betta Fish Is Laying At The Bottom Of The Tank.https://www.aquariumsource.com/betta-fish-laying-at-bottom-of-tank/

Betta Fish Just Laying Around. https://nippyfish.net/2007/01/22/betta-fish-just-laying-around/