If you’ve noticed your fish sitting still at the bottom or top of the tank while still breathing, it can be alarming. A fish that is breathing but largely immobile likely indicates a health problem. But don’t panic, this article will cover the full reasons why your fish may be breathing but not moving and what you can do about it.
If you’re short on time, here’s a quick answer: Lack of movement in an otherwise breathing fish is most often caused by stress, shock, disease, or old age. Test and improve water conditions, separate sick fish, and consult an aquarium specialist if the behavior persists.
Shock
Temperature Shock
Sudden changes in water temperature can shock fish and cause serious stress. Fish are cold blooded and can only thrive in water temperatures they are adapted to. If the temperature rapidly increases or decreases by more than 2-3 degrees Fahrenheit, it can be extremely dangerous for your fish.
Some common causes of temperature shock include:
- Adding cold water during water changes
- Heater or chiller failure
- Power outages
- Moving tank to different room
The effects of temperature shock may not be immediately visible. It can cause cell damage, a weakened immune system, disease, and even death over time. Watch for symptoms like rapid breathing, loss of color, lethargy, and erratic swimming.
To prevent temperature shock, invest in a high quality heater and thermometer. Make water changes gradual by dripping new water into the tank over several hours. Have a backup battery or generator for power outages. When transporting fish, bag them and allow time to adjust to any temperature changes.
pH Shock
pH shock occurs when there is a sudden change in the pH of the aquarium water. Fish have adapted to live in water of a specific pH range and any fluctuations can cause them stress.
Some common causes of pH shock include:
- Improper acclimation of new fish
- Incorrect pH of replacement water during water changes
- Adding too many chemicals or additives at once
- Filter media disruption or failure
The effects of pH shock include erratic swimming, gasping, increased mucus production, loss of appetite, and increased susceptibility to disease. At extreme pH levels, it can burn the skin, eyes, and gills.
To avoid pH shock, test pH regularly and make adjustments slowly over several hours or days. Use pH buffers, driftwood, rock, and plants to help stabilize pH. Acclimate new fish gradually. Maintain proper tank maintenance and filtration to control pH drift.
Ammonia Shock
Ammonia is produced as fish waste and uneaten food breaks down in the aquarium. High ammonia levels are extremely toxic to fish. Ammonia shock occurs when ammonia spikes to unsafe levels, poisoning the fish.
Some common causes of ammonia spikes include:
- Overfeeding
- Overstocking tank
- Dead fish or decaying matter
- New tank that isn’t cycled
- Filter failure
At low levels, ammonia can cause irritation, respiratory distress, reduced appetite, and increased susceptibility to disease. At higher concentrations, it can quickly burn the gills, eyes, skin, and internal organs, leading to death.
Test for ammonia regularly and perform partial water changes if levels rise. Don’t overfeed and properly cycle a new tank. Use live plants and chemical media to help control ammonia. Remove any dead fish immediately to prevent spikes.
Stress
Overcrowding
Overcrowding is one of the most common causes of stress in aquarium fish. When too many fish are kept in a tank that is too small, it can quickly lead to deteriorating water quality, increased aggression, and stress. Fish need adequate room to swim and hide.
General rules of thumb are 1 inch of medium sized fish per gallon of water, or 1 fish per 2-3 gallons for larger fish like goldfish. However, these are just guidelines, and factors like filtration capacity and fish species should be considered.
Overcrowded tanks often lead to spikes in ammonia and nitrites as waste accumulates faster than the filtration can handle. This poor water quality is extremely stressful and can leach protective mucus layers from fish gills and skin.
In addition, cramped quarters lead to more aggression and fighting between fish as they compete for resources and try to establish territory. Providing an adequately sized tank for the fish species and number of fish, and maintaining high water quality through filtration, partial water changes, and tank maintenance are key to avoiding the stress of an overcrowded tank.
Aggressive Tankmates
Housing fish species that are overtly aggressive or predatory with more passive tankmates is a recipe for stress, injury, and potentially death in the fish community. Some common aggressive species that can intimidate and terrorize tankmates include cichlids like oscars and Jack Dempseys, large plecos, tiger barbs, and crayfish.
More passive fish like guppies, tetras, and goldfish can become extremely stressed and nipped by these aggressive fish, leading to health issues like frayed fins, bodily injury, appetite loss, and secondary infections.
Careful research should be done prior to mixing species to avoid incompatible fish. Aggressive fish are best housed alone or with others of similar temperament and size to reduce chances of bullying. Providing adequate tank space and hiding spots like plants, rocks or driftwood can help diffuse aggression too.
Removing overly aggressive fish promptly also reduces stress on other tank inhabitants. With some species combinations, aggression and intimidation are unavoidable, underscoring the importance of proper fish selection and tankmate choice when stocking an aquarium.
Sudden Changes
Sudden changes and fluctuations in aquarium conditions are very stressful for fish. Altering water chemistry too drastically, shifting water temperature rapidly, or modifying tank layouts can cause major distress.
Fish become conditioned to stable tank parameters and sudden swings can cause physiological shock. For example, rapid 25% water changes with very different temperature or pH from the tank water can harm fish health.
Likewise, quick temperature spikes from equipment failure or adding cold water can also be problematic. Fish subjected to sudden changes often show signs of respiratory distress like gasping at the surface, become lethargic, stop eating, or display erratic swimming.
Gradual acclimation over an hour or more allows fish to adjust to new water conditions and avoid abrupt shifts. When cleaning filters or decor, replacing no more than 25% of the water at a time avoids major fluctuations as well.
Providing consistent, stable water quality and tank conditions prevents unnecessary stress on fish.
Poor Water Quality
Chronic exposure to poor water quality is tremendously stressful and dangerous for aquarium fish. As ammonia, nitrite, nitrate, phosphates, and organic waste accumulate from fish, decaying food, etc., water toxicity increases substantially.
Prolonged poor water chemistry erodes gill tissues, inhibits oxygen uptake, hinders immune function, and damages organs throughout the body according to research. Common symptoms of poor water quality’s stress include clamped fins, gasping, lethargy, loss of appetite, reddened gills, erratic swimming, and fish hovering near water outlets and the surface.
While all fish are impacted, certain species like discus, clown loaches, and cardinal tetras are especially sensitive to deteriorating water conditions. Regular testing with liquid kits, partial water changes, gravel vacuuming, filter cleaning, and using live plants and chemical media all help lower waste levels.
Providing pristine water quality is crucial to avoid one of the most common and avoidable stressors plaguing aquarium fish. If issues persist, increasing water changes, adding aeration, or medication may be required to protect fish health.
Disease
Bacterial Infections
Bacterial infections are a common cause of fish not moving but still breathing. Pathogenic bacteria like Aeromonas, Pseudomonas, and Mycobacterium can infect the internal organs, skin, gills, and fins of fish. Here are some of the most common bacterial diseases in aquarium fish:
- Fin and Tail Rot – Caused by bacteria eroding the tissue of fins and tail. Affected areas appear frayed and discolored.
- Dropsy – Bacterial infection of internal organs leading to swelling of the belly and raised scales.
- Fish Tuberculosis – Chronic wasting disease caused by Mycobacterium. Fish become emaciated and develop skin ulcers.
- Gill Disease – Bacterial infection of the gills leading to increased breathing rate and lethargy.
Bacterial diseases are treated with antibiotics, but prevention through good water quality and reduced stress is key. Use a gram-negative antibiotic like kanamycin for stubborn infections.
Parasites
Parasitic worms, protozoa, and crustaceans can weaken fish and cause labored breathing. Common aquarium parasites include:
- Ichthyophthirius (Ich) – Protozoan parasite that causes small white dots all over fish.
- Velvet Disease – Caused by dinoflagellates which leads to yellowish coating on skin.
- Gill Flukes – Microscopic worms that feed on gill tissue and impair respiration.
- Fish Lice – Crustacean parasites that attach to fish and feed on mucus, tissue.
Heavy infestations of parasites can seriously impair a fish’s breathing. Treatment involves medications like formaldehyde, malachite green, and praziquantel. Improving water quality and adding aquarium salt helps prevent recurrence.
Fungal Infections
Fungi like Saprolegnia thrive in poor water conditions and can infect fish, especially if their immune system is weak or skin damaged. Fungal infections often show up as fuzzy white patches on the body, mouth, or fins. The fungi interfere with oxygen absorption across the gills and skin of fish.
Fungal infections are treated with antifungal chemicals like methylene blue, malachite green, and potassium permanganate. Reducing organic waste and maintaining good water quality helps prevent fungal growth in the aquarium.
Viral Infections
Viruses are an uncommon cause of lethargy and breathing issues in aquarium fish. However, some viruses like viral hemorrhagic septicemia virus (VHSV) can attack internal organs and impair breathing. Other viruses like infectious spleen and kidney necrosis virus (ISKNV) cause chronic wasting away.
Unfortunately, there are no treatments for viral infections in fish. Prevention through quarantine and disinfection is important. Using ultraviolet sterilizers in the aquarium can help deactivate viruses and other pathogens.
Old Age
Slowing Metabolism
As fish age, their metabolism begins to slow down. This means their bodies convert food and oxygen into energy at a slower rate. An older fish’s digestion becomes less efficient, making it harder for them to get nutrients from food. Their cells also undergo more wear and tear over time.
With a slower metabolism, older fish tend to be less active. You may notice they swim slower and spend more time resting than younger fish. Their fins may appear more frayed and worn down as well.
Weakening Immune System
A fish’s immune system also declines with age, making them more vulnerable to diseases. Their mucus coat thins, so parasites and bacteria have an easier time penetrating their skin and gills. On top of that, their kidney and liver function tends to deteriorate.
These age-related immune deficiencies mean older fish get sick more often. Once infected, they also have a harder time recovering. You may observe symptoms like frayed fins, cloudy eyes, reddened areas, or white fuzzy patches on their body.
When to Seek Help
No Improvement After Addressing Possible Causes
If your fish is still having breathing issues after you’ve addressed potential environmental stressors, it may be time to seek professional help. Here are some signs that your fish’s labored breathing may require veterinary intervention:
- No change or worsening of symptoms after improving water quality, adjusting temperature, reducing stressors, etc.
- Breathing becomes more rapid or exaggerated over 24-48 hours.
- Fish struggles to reach the surface for air.
- Fish seems exhausted from the effort to breathe and has trouble swimming.
Fish veterinarians have specialized tools and medications to help diagnose and treat respiratory issues in fish. For example, they may take radiographs (x-rays) to check for internal tumors or fluid accumulation. Or they may prescribe antibiotics or corticosteroids to reduce inflammation.
Don’t hesitate to reach out to an aquatic veterinarian if your fish’s condition does not improve.
Not Eating
Loss of appetite often accompanies labored breathing in fish. This is because sick fish tend to conserve their energy for vital functions like respiration rather than eating. According to one 2021 study, 76% of pet fish presented to veterinarians for respiratory problems also had anorexia.
Here are some tips if your fish stops eating:
- Offer small, frequent meals rather than large meals to reduce effort.
- Try soaking food in garlic juice or vitamin supplements to stimulate appetite.
- Use foods high in aroma like brine shrimp, bloodworms or daphnia to trigger a feeding response.
- Assist weak fish by guiding food to their mouths with tweezers.
If your fish goes more than 5 days without eating, an underlying illness is likely at play. Seek veterinary help to identify and address the primary problem.
Lethargy Lasting Over 48 Hours
It’s normal for fish to have periods of low activity. But consistent lethargy and lack of response to stimuli for more than 48 hours often signals an health issue. Labored breathing accompanied by prolonged lethargy can indicate:
- Oxygen deprivation from poor water quality
- Pain or discomfort from illness or injury
- Metabolic disorders like organ failure
- Infections affecting vital systems
By the time lethargy sets in, your fish may already be in critical condition. Don’t wait longer than 48 hours to seek emergency veterinary care. Bring a water sample so the vet can test for toxins, parasites or dangerous oxygen/pH levels.
With rapid diagnosis and therapy, many fish can make a full recovery from respiratory distress and associated lethargy. So don’t delay – at the first sign of labored breathing and inactivity in your aquatic pet, take action. Their life may depend on your attentiveness and quick response!
Conclusion
Lack of movement in an otherwise breathing fish is cause for concern and investigation. By methodically testing water parameters, observing tankmates, and inspecting your fish closely, you can likely determine the cause and take appropriate action. Seek professional advice if problems persist.
With attentive care and a stress-free environment, your fish may recover and regain its normal activity levels.