Behavior when Aquarium fish swim at the surfaceIt is often the first and most alarming signal of a critical drop in dissolved oxygen or toxic water poisoning by ammonia. Under normal habitat conditions, hydrobionts occupy different horizons of the reservoir depending on the species, but mass surfacing and swallowing air with the mouth indicates acute hypoxia or systemic failure in the biological equilibrium of the system. Ignoring this symptom in the first hours can lead to mass death of the entire population of the aquarium or pond, as the tissues of the body begin to suffer from suffocation faster than the owner has time to react.
It is necessary to immediately assess the state of the water and the behavior of specific individuals, as the causes can range from banal overpopulation to complex infectious diseases of gills. GoldfishThey are more sensitive to environmental parameters than guramami, which have a labyrinth organ and can periodically capture atmospheric air. However, if species that do not have this physiological feature rise to the surface, or if fish rub against the scenery and convulsively swallow air, this requires immediate intervention and rapid water tests.
Oxygen starvation as the main cause of surfacing
The most common reason fish swim near the surface is a banal decrease in the concentration of oxygen in the water below a critical level. In warm water, the ability of the gas to dissolve decreases, and the metabolism of cold-blooded inhabitants accelerates, which leads to a double effect: more oxygen is needed, and less oxygen is in water. This is especially common on hot summer days in outdoor ponds or in overcrowded aquariums with aeration turned off at night.
When hypoxia occurs, fish instinctively rise to the upper layers, where the concentration of oxygen is maximum due to contact with the atmosphere. They often open and close the gill covers, trying to drive more water through the gills to extract residual gas. If not, compressor or not to increase the filtration, creating ripples on the surface, the suffocation process will progress, leading to lethargy and loss of coordination.
- 🌡️ A sharp increase in water temperature above 28-30 degrees Celsius, which reduces the solubility of gases.
- 🌿 Exuberant proliferation of plants that absorb oxygen at night and emit carbon dioxide.
- 📉 Disabling filtration or aeration for a long time, which stops gas exchange.
- 🐟 Excessive overpopulation of the aquarium, when the biomass of fish exceeds the capabilities of the oxygen saturation system.
⚠️ If fish are choking, do not feed them at this time. Digestion of food requires a huge amount of oxygen, which will kill the weakened body.
For emergency oxygenation of water, hydrogen peroxide (3%) can be used at the rate of 1 ml per 10 liters of water, but this is a temporary measure until aeration is established.
Toxic poisoning and quality of the aquatic environment
The second most important cause of surfacing is chemical poisoning, most often ammonia or nitrites. These compounds are released as a result of the decomposition of organic matter: food residues, fish excrement and dead plant parts. In a young or overloaded aquarium, colonies of nitrifying bacteria do not have time to process poisonous ammonia into less dangerous nitrates, which leads to chemical burns of the gill apparatus.
Damaged gills lose their ability to efficiently extract oxygen even from gas-rich water, so the fish are forced to climb up to try to breathe. In such cases, there is not just surfacing, but a characteristic “suspend” at the surface with wide-open gills. Water testing shows high concentrations NH3/NH4 and NO2This requires immediate water replacement and air conditioning.
Also, the cause can be chlorine or heavy metals that have fallen into the water when improperly substituted. Chlorine causes burns to the mucous membrane, blocking breathing, which causes fish to rush near the surface in search of salvation. It is important to always protect tap water or use special dechlorinators before adding fresh water to the system.
☑️ Verification of water parameters
Diseases of gills and infectious causes
If the water parameters are normal, but the fish still swim near the surface, infectious or parasitic diseases should be suspected. One of the most dangerous ailments is gill rot (flavobacteriosis), caused by bacteria. Flavobacterium columnare. The bacteria destroy the gill petals, causing tissue necrosis that physically prevents the fish from breathing, forcing it to seek air near the surface.
Another common problem is parasites such as Costia or ChilodonellaThey are the ones who are in the swelling and the ones who are in the swelling. Mucus clogs the gill petals, creating a barrier for gas exchange. The fish becomes sluggish, loses appetite, swims at the surface or at the bottom, often making sharp jerks and trying to scratch the ground.
- 🦠 Pale pink or gray plaque on the gill petals, visible when the gill cover is extended.
- 💨 Sticking of gill petals, which reduces the area of oxygen absorption.
- 🩸 Hemorrhages or necrotic areas on the gill arches.
- 📉 A sharp decrease in immunity and refusal of food against the background of suffocation.
Treatment in such cases requires the use of specialized antibiotics or broad-spectrum antiparasitic drugs. It is important to isolate sick fish in a sediment, as infections are quickly transmitted through water and common care items.
Method of examination of gills
Carefully lift the gill cover with tweezers or a wet stick. Healthy gills have a bright red color. If they are pale, brown or covered with mucus - this is a sign of pathology.
Overfeeding and problems with the swimming bladder
Fish often swim near the surface not because of lack of oxygen, but because of problems with the swim bladder, which occur due to overfeeding or using poor-quality dry food. Swelling in the stomach, the feed granules press on the swimming bladder, shifting the center of gravity and disrupting hydrostatics. The fish begins to “surface” and cannot sink to the bottom while remaining near the surface.
Selection forms are particularly susceptible to this phenomenon. goldfish and scalar. In this case, the fish does not swallow convulsive air, but simply passively holds at the water mirror, sometimes falling on its side. The solution to the problem lies in the correction of the diet: the transition to feed that does not swell in water, and the addition of plant fiber.
For prevention, it is necessary to arrange fasting days and not give food more often 1-2 times a day in small portions that are eaten in 2-3 minutes. Dry food is better to soak in water before it swells before entering the stomach of the fish.
Temperature shock and stressors
Sharp fluctuations in water temperature or chemical composition can cause severe stress, which manifests itself in inadequate behaviors, including surfacing. If you just changed the water and the fish went up, perhaps the parameters of the new water (temperature, pH, hardness) were too different from the aquarium. For fish, this is equivalent to getting a person into conditions of a sharp change in atmospheric pressure.
Stress can also be caused by external factors: loud noises, blows to glass, bright lights or the appearance of new aggressive neighbors. In a state of panic, fish can rush chaotically throughout the volume, including jumping out of the water or pressing against the surface. Minimizing external stimuli and darkening the aquarium helps calm the hydrobionts.
| Symptoms. | Probable cause | Action. |
|---|---|---|
| Convulsive air ingestion | Lack of oxygen (hypoxia) | Turn on aeration, replace 30% of water |
| The fish hangs upside down, but breathes | Ammonia poisoning | Urgent replacement of 50% water, siphon of the soil |
| Passiveness at the surface | Overeating/bubble | Fasting 2-3 days, feeding peas |
| Redness of the gill threads | Infection or chemical burn | Water test, application of air conditioners, treatment |
Specificity of behavior of different types of fish
It is important to distinguish between pathological surfacing and natural behavior. There are species called Anabassic, which have a special labyrinth organ and duty periodically capture atmospheric air. They're included guramami, macropods, cock and lyalius. If these fish swim near the surface and make characteristic swallowing movements, this is the norm, not a sign of disease.
However, if labyrinth fish begin to swim sideways, lose color or hide, this may indicate that even atmospheric air becomes scarce due to vapor organics or high temperature above the water. In such cases, it is necessary to monitor the temperature regime and the purity of the water surface, removing the bacterial film.
Bottom fish, such as corridors or catfishWhen surfacing to the surface, almost always signal a critical situation. For them, this is an unnatural behavior that suggests that the conditions at the bottom have become unbearable (accumulation of hydrogen sulfide, lack of water current) or the fish is seriously ill.
⚠️ Note: Do not confuse the normal behavior of labyrinth fish with signs of suffocation. Gurams should breathe air, but they should not hang at the surface motionless and heavy breathing.
Emergency measures and prevention
When fish are found swimming near the surface, you need to act quickly and consistently. The first step should always be to check the water parameters with tests, as the visual evaluation is often misleading. If there are no tests, 30-50% of water is replaced with fresh, settled water of the same temperature, which instantly reduces the concentration of toxins and saturates the water with oxygen.
It is necessary to increase aeration by lowering the sprayer closer to the bottom or adding a second compressor. Creating active water movement on the surface contributes to rapid gas exchange. If the reason is overfeeding, feeding is stopped completely for a few days before the normalization of behavior.
- 🔍 Daily visual examination of fish and feeding behavior.
- 🧪 Regular water testing for ammonia and nitrites, especially in new aquariums.
- 🌡️ Control of temperature and purity of filtering materials.
- 🥗 Compliance with feeding regime and use of quality feed.
Prevention is always more effective than treatment. Regular water changes, soil siphon and control of the population density of the aquarium avoid most problems related to water quality. Remember that clear water does not always mean healthy water, so chemical control remains an essential tool for the aquarist.
The main conclusion: The surfacing of fish is a symptom, not a disease. The success of treatment depends on the exact cause: oxygen, chemistry, or infection.
Why do fish swim at the surface after water changes?
This can be caused by a temperature shock if the new water was colder or hotter than the aquarium. It is also possible to have chlorine or chloramine in tap water if no air conditioning is used. A sharp change in pH (for example, when adding too soft or hard water) also causes stress and surfacing.
How quickly will an oxygen compressor raise O2 levels?
With active aeration, oxygen saturation of water occurs quite quickly, within 15-30 minutes you can notice an improvement in the condition of fish. However, complete alignment of parameters and weathering of gases can take up to several hours. In emergency cases, strong water spraying through the filter helps.
Can a fish die from overeating at the surface?
Yes, a strong bloating of the abdomen from the feed can lead to compression of the internal organs and the swimming bladder, which disrupts buoyancy and blood circulation. If the fish is inflated so that it has lost the ability to dive, the risk of death without fasting and treatment is high.
What if fish swim at the surface at night?
At night, plants stop photosynthesizing and begin to consume oxygen, releasing CO2. If the aeration is turned off at night, oxygen starvation may occur in densely overgrown aquariums. Solution: Do not turn off the compressor overnight or reduce the number of plants/population.