Why is my fish lying at the bottom of the tank? A complete guide

If your fish is lying at the bottom of the tank, it could be for a variety of reasons like water quality imbalances, illness or intoxication. It’s necessary to note that some fish use the floor surface to relax, so recognising the symptoms of an unhealthy fish is important.

Why is My Fish Lying at the Bottom of the Tank?

In most cases, a fish will lie close to the floor of the tank when ill or injured, and there may be various signs that can help you perceive this and/or find the cause.

Such signs can include weakness, loss of appetite, heavy breathing, slow movements and loss of buoyancy. We elaborate on this below.

Appetite Loss and Lying on the Bottom of the Tank

If your fish isn’t eating and remains mostly at the bottom of the tank, there’s a high chance it may be unwell. Illnesses such as dropsy, swimming bladder diseases and common constipation can cause appetite loss.

You may have to try different foods to encourage your fish to eat. Live, fresh and frozen foods are good choices for sick or recovering fish, and you can also add blanched vegetables or change fish flakes.

Breathing Heavily and Lying on the Bottom of the Tank

If your fish seem to be laying on the floor of the aquarium and gasping for air, it’s most likely linked to water parameters. Your tank water could have ammonia poisoning, nitrate poisoning or temperatures that are too hot. In this case, you’re best to fix water conditions as quickly as possible. If the problem is heating, cool the tank slowly as sudden changes can cause extra stress on your fish.

Laying Upside Down on the Bottom of the Tank

Watching your fish lying upside-down is a significant red light. It is an indication that the fish have bladder disease. If they are still breathing or trying to move their fins, you may be able to tell if something internal happens. Proceed with a good water change, permanently stabilizing the water parameters that enter with the one that leaves. Reduce the flow in the aquarium and waiting things out.

Being upside-down is an indication that the fish may have swim bladder disease.

What causes a fish to lay on its side?

Fish sometimes can relax or sleep by his side and not be upright. You can give your fish more decor, plants, and hiding options if you want them away from substrate; there are also many sleeping platforms and artificial caves for sleeping fish available at specialized stores. Take a closer look at the gills to be sure they are breathing and healthy.

Why your fish is lying at the bottom of the tank

There are several possible reasons for a fish to stay in the bottom of the tank. Sometimes the fish is just relaxing; sometimes, it is signing that something in the tank is wrong. Not every reason is terrible, but the why of your fish at the bottom can explain them with this guide. Use positional and behavioral signs to identify and diagnose problems.

Why is your goldfish at the bottom of the tank?

Goldfish lying at the bottom of the tank are often warning signs of a problem. When left untreated, these conditions often turn worse – resulting in death. Fortunately, when treated early, your fish will make a proper recovery.

Is it normal for betta fish to lay on the bottom of the tank?

There are several reasons bettas laying at the bottom of the tank; some are common and harmless. Learn to understand which is which will help you with whatever challenges your Betta might have. Understanding if they are suffering from stress can help with the treatment of your animal.

Sleeping Betta Fish

A healthy Betta fish will take up his naps often. If you aren’t sure if your Betta is simply tired, observe the fish closely. Watch for signs of stressors and illness. Most fish will move from lying on their side to lying in the new rest place. It’s usually a sign that your fish is good, especially when you see it at the bottom. You can also place a resting place over your water tank to determine if fish are going to get tired from sleeping.

Older Bettas like to rest at the bottom.

Some older betta fish don’t have the stamina to swim in the tank. Betta fish generally live three to five years and are sometimes more likely to need rest as they turn older. Bettas also prefer a slow, gentle water flow, something that is particularly important for older fishes. You can also give Betta a resting place in the tank’s bottom for relaxation and restorative rest. For more information, check on our betta articles.

What if your Betta is at the bottom of the tank, not moving?

When your fish is not moving, you need to do an inspection. It may have heat shock, be intoxicated or have a swimming bladder disease. When you see these signs, you must act quickly, you can reduce water flow to help you fish, but it’s essentially a waiting game until you can correctly diagnose the problem.

Troubleshooting Guide: if your fish is lying on the bottom of the tank

Fish can go to the bottom to hide, lay eggs, or sleeping. In most cases, it could be a sign of trouble. It is not uncommon to find tiny white spots on the fish indicating some disease. Try to net it to see if the fish is alert and immediately try to detect symptoms. If some sickness is detected, it should go to a hospital tank and medicate according to the other signs and symptoms you find.

Diseases That Can Cause Fish To Lay At The Bottom Of The Tank

As a precaution, always quarantine fish in a hospital or quarantine tank, watching their condition. Isolating diseased fish in a stable and confined environment facilitates care of water patterns, dosage, and application of medications and makes the fish easily visible to the guardian. Noticing a disease’s first sign can help you deal with the illness at its earliest stage. Learn about what conditions cause fish to lay on the bottom of the tank.

Sickness & Disease

Fish can have several diseases. In most cases, fish are more likely to get an infection because of a weaker immune system, often caused by stress or bad environmental conditions. Diseases like ich, bloat, dropsy, and others can affect more vulnerable fish. Stay ahead of water conditions and ensure that parameters are within the acceptable range.

Ammonia poisoning

It is pretty easy to monitor for ammonia poisoning. You can use an ammonia test kit to know the concentration in your tank. This can be reduced with a new tank that’s been cycled before it’s populated. Keep the tank clean, make your gular maintenance with water changes, clean the substrate, avoid overfeeding, and invest in an effective filter.

Nitrate poisoning

Fish with toxic nitrate might be breathing severely and exhibiting pale discolorations. They might also appear lazy and lay at the bottom of the tank. Test the water on the tank to check nitrate concentrations. If the nitrates are too high, perform a significant water change.

Aggressive fish

Some aggressive fish can attack and injure other fish, causing them to get injured lying on the substrate. There are many reasons for finding fish in the bottom of the tank. Some situations may require the use of medication. Other conditions could require adjustment. It’s also important to check the exact reason before starting therapy as it may not become necessary for treatment alone. For example, remove the aggressive fish or place the timid fish in a floating basket may solve the problem.


Too many fish in a small tank increases their stress levels. The more fish in tanks, the lower the chance is that ammonia will enter the system. A fish can also lay at the bottom of the tank because of overcrowding in the tank.

Swim Bladder Disease

Swim bladder problems are frequently caused by overfeeding or the inability of an animal’s body to digest some food. Give fish some thawed green peas or daphnia to aid in combating swimmers’ bladder disease. To avoid a problem with constipation, avoid overfeeding the fish. Once it feels better, it should start swimming as usual. A fish’s bladder helps its body float when the body gets full of fluids. When it’s healthy, the swimmer’s swim bladder allows the fish to swim and float in aquariums in most stages. When a fish has an internal swimming bladder infection, they either get stuck floating at the water surface or the bottom of the tank.

Other stress-related issues

Have some of its fellow tankmates harassed the fish? Try offering fish a more extensive area or moving to a private aquarium. If someone thinks that their fish is injured, you should isolate and treat it. When the fish is under stress, its color can be stained in any manner. If the fish has a disease or bacteria, you might have to apply medications.

All possible causes

Understanding your fish behavior can help you identify when you need to take action. Here are some of the more common reasons that fish lay in the aquarium.

Displaying territorial behavior at the bottom level

Some territorial fish could stay in the bottom part of the tank and claim a portion of its land. You can not ignore fighting and aggression. Solutions include the place the angry fish in a new aquarium.

The water temperature is either too low or too high.

If the water temperature in your aquarium falls too low, the creatures will rest motionless on the bottom of the tank to conserve energy. High temperatures make it difficult for the water to absorb oxygen during gas exchange; this makes the fish breathe heavily and become stagnant at the bottom of the tank. Sudden changes in water temperatures are dangerous situations to be dealt with. Fish kept in high temperatures also exhibit a more accelerate metabolic rate, eating much more and then cause more waste.

The water is too cold.

You may choose a water temperature around 77 degrees Fahrenheit. If the temperature gets below these levels, the metabolism of most tropical freshwater fish starts to slow down. Your fish may become very lethargic and weak, lying at the bottom of the tank. Use an in-tank heater to raise the temperature in the aquarium gradually. Do not try to use anything that will cause a sudden temperature change. If you don’t increase the temperature slowly, your fish could feel stressed and have future diseases.

The water is too hot.

Warm water releases oxygen very quickly. Without enough oxygen in the water, your fish will be gasping for water below. Running water without adequate oxygen poses a considerable challenge for fish and bacteria, which helps the tank go without further issues. You can use a fan to cool off the temperature slowly. Use an air pump to restore perfect oxygen levels into your water.

A significant drop in water quality and unstable water parameters

An enormous red flag is a sudden change of some characteristic or behavior in your fish. Some fish species would lay down in their tank when the water was not good enough to maintain their survival. These sensitive animals are especially vulnerable to intoxication and the disease itself. The signs that your fish have some virus or bacteria can cause the virus, and it’s not uncommon for animals kept under horrible water conditions. Stress-induced a drop in fish immunity. If your fish lay on the bottom or is showing other symptoms, isolate them.

The aquarium is not large enough.

Many fishkeepers make huge mistakes thinking that fish can live and thrive everywhere under the water. In tiny spaces, fish have little to no room to swim around; this can be very stressful to any animal. Think about increasing the capacity of your tank. You should also implement various enrichment elements for your fish. Some implements include caves, plants, and natural decorative items. All this is important for keeping your fish happy and healthy. Within small spaces, your fish will suddenly lose interest in life, so they can’t do anything else but sit on the tank bottom. This is just not how people should keep their fish. Give your fish more room and space to explore.

They’re sleeping.

Some fish follow the same overall sleep cycle as humans. They sleep at night and are active throughout the day. If you notice your fish sleeping in the morning, consider your light night settings. Leave your fish in a dark, quiet environment at night to ensure they get the necessary rest. Bettas are known for finding genuinely interesting places to sleep. They can tuck into corners under the plants or even rest in the mossy foliage. If your fish do not get enough sleep at night, you can probably observe them napping at the bottom of the tank.

Extreme current

Some fish don’t cope well in powerful water flow. When you have a strong flow coming from the filter or some pump, that will cause stress on the fish. To decrease water flow from your pump, attach a sponge filter. Alternate, you can redirect a current toward plants and decorations. Breaking through the current will help reduce flow throughout the aquarium. Your fish might have decided to rest by lying on the bottom of the tank after being removed from a fast-flowing tank.

Hiding at the bottom of the tank

Red flags include fish that chose to hide at the bottom of the tank. Monitor the fish and see what happens when it starts trying to get off the bottom. The fish may be getting harassed or threatened, meaning tank mates incompatibility problems.

Bottom dwellers

Some loaches, corys, catfishes, and plecos are perfect examples of some bottom dwellers living in the aquarium’s lower parts. Some tropical fish of this type will not feel very comfortable in heavily planted tanks, preferring to occupy open areas of the aquarium.

Bottom feeders

Many bottom dwellers also feed on bottoms. They prefer wandering down the bottom tank because there is where they can get some food. These fish are usually feeding all the time. They provide when the food is offered to them and then look for leftovers in the tank.

Visible wounds

Open wounds lead to illness. Quarantine is also needed to save a wounded fish from the potential repercussions of having the tankmates opportunistically harass them, also from opportunistic severe bacterial infections. A quarantine prevents injured fish from being safe from other tank mates.

Older fish

Aquarium fish generally have an average lifespan, for the most part above 3 to 8 years. As these pets age, the fish could have had higher chances of resting in the tanks near the bottom of the tank. During the interval between periods of activity, short breaks to rest should no longer be concerned.


When artificial aquatic habitats as aquariums and ponds lack refuge areas, most newcomers fish will prefer to lay at the bottom. Healthy fish will recover quickly, leaving the substrate and exploring their new home; weakened fish already show another behavior; always choose healthy animals and quarantine new fish before placing them in your main aquarium.

Fish lay on the bottom because of STRESS.

Fish will sink out to the bottom of the tank and fade in color when exposed to stress. Stress arises through external and internal influencing forces, like water parameters, correct tank mates, food quality, etc.

What should I do if my old fish is lying on the bottom of the tank for too long?

At that moment, some fish can be approaching the last step in their biological cycle. Fish can develop many different stages of their life span, and many will probably pass early. If you didn’t raise your fish, you wouldn’t know his age when you acquired him. His life cycle may be reduced if he is wild-caught or has some disease or genetic dysfunction. If the other fish in the same tank appears with these the same signs, it’s worth checking the whole aquarium to see if there is some disease outbreak or bad water quality. Alternatively, if you notice unusual behavior or activity, do not hesitate to relocate your fish to a hospital tank and keep an eye open before treating it with medicine.

Tips for Beginners Fishkeepers

Some fish, such as bettas, spend a lot of time lying at the aquarium’s bottom. Ask the store owner where you buy your fish about the activity levels that you should expect in this particular species. Set time for your daily care routine. Check your equipment to ensure the filter and heaters are on, and the lights are working in a good day/night cycle. Use the daily care routine to check on your fish and see that everyone is eating like always and behaving in a usual fashion. Set up a periodic cleaning routine for the aquarium, constantly changing the water and vacuuming the substrate. Remember, the tank must be adjusted to the fish, so keep the water parameters healthy and don’t overstock your tank; degraded water can make your fish lay at the bottom.

Final Comments

It would help if you worried when the fish lay at the bottom of the tank. Consider adding other accessories as well as live plants to your decor. Your fish uses it to rest without feeling exposed or vulnerable. Resting without staying at stress will allow your fish to feel secure for long periods. In terms of behavior, it is generally advisable to keep an eye on the fish, especially if this is a new addition to your tank. The fish should feel comfortable and active during the day. Fish that lay at the bottom can also signify that something is not right in the aquarium. Keep watching to see if everything is ok, otherwise isolate the fish in a hospital aquarium, and follow this guide.