In aquaculture and ornamental fish keeping, fish gas bubble disease is a problem that cannot be ignored. When the gas in the water is supersaturated, fish absorb these gases, and bubbles will form in the fish’s body, thus triggering gas bubble disease. This disease is quite harmful to the health of fish and can even lead to the death of fish in severe cases. Understanding the relevant knowledge of fish gas bubble disease is crucial for protecting the health of fish.
What is Fish Gas Bubble Disease
Fish gas bubble disease is a condition in which microbubbles form in the tissues and blood vessels due to gas supersaturation in the water. Bubbles may appear in the fish’s eyes, fins, skin, and internal organs. Microbubbles may combine into larger bubbles, obstructing blood flow and causing diseases, including fin and organ necrosis. It should be noted that fish gas bubble disease is different from buoyancy disorders such as swim bladder disease. The formation of bubbles in diseased fish is similar to the decompression sickness that divers suffer from, which is commonly known as “the bends.”
Symptoms of Gas Bubble Disease in Freshwater Fish
- Abnormal behavior: Diseased fish may show disorientation or restlessness and often swim towards the water surface.
- Visible bubbles on the body surface: Obvious bubbles can be seen on the eyes, skin, or fins. Bubbles are often visible in the anterior chamber behind the cornea of the eye. Bubbles on the skin surface may appear as external lumps and can be felt by moving a hand along the fish. Bubbles can also be seen between the fin rays in the transparent membrane of the fins.
- Appearance changes: The eyes protrude (one or both), and the skin color darkens.
In addition, the water in the aquarium may be observed to become cloudy, with tiny bubbles on plants and the aquarium walls. To determine whether the water turbidity is caused by microbubbles, take a glass of the cloudy water and let it stand for 30 – 45 minutes. If the turbidity is caused by suspended particles in the water, there will be a layer of sediment at the bottom of the glass; if it is microbubbles, the water will become clear, and there may be bubbles adhering to the inner wall of the glass, just like the bubbles in champagne.
Causes of Fish Gas Bubble Disease
- Gas supersaturation: Fish gas bubble disease is mainly caused by gas supersaturation in the aquarium water. Fish absorb these supersaturated gases, and the gases accumulate in their bodies. Gas supersaturation usually occurs when the amount of gas in the water is excessive relative to the temperature, salinity, and atmospheric pressure. Among them, excessive nitrogen is the most common cause of fish gas bubble disease, while carbon dioxide and oxygen bubbles are also possible, but these gases are often used by fish tissues and can be processed relatively quickly.
- Equipment failure: The most common cause in home aquariums is a cracked or poorly connected pipe or filtration component. A small hole can allow tiny air bubbles to be sucked in by the water flow through the filtration system, resulting in gas supersaturation.
- Waterfall features: Bubbles are likely to be introduced at the bottom of a tall waterfall or fountain feature. In an aquarium, when the water is not filled to the top, the mixing of the waterfall water with the lower – level water can generate bubbles of various sizes. Depending on the water temperature and bioload, these bubbles may cause gas supersaturation in the water.
- Water changes: Sudden changes in water temperature can cause bubbles to form because the partial pressure of a gas changes with water temperature. This often occurs when the water added to the aquarium is significantly warmer or cooler than the current water temperature.
- Weather: Gas supersaturation may occur when the total pressure of gases in the water is higher than the surrounding atmospheric pressure. Depending on the setup of the aquarium and the surrounding environment, simple atmospheric weather changes can lead to the formation of microbubbles.
- Algae growth: In ponds with abundant algae growth or in aquariums with many plants and high – intensity lighting, algae and plants produce oxygen through photosynthesis, which may supersaturate the water with oxygen. Tiny bubbles will be seen on the plant leaves or algae strands. If the water temperature is high, gas bubble disease may be triggered.
How Veterinarians Diagnose Fish Gas Bubble Disease
- Physical examination: Most cases of gas bubble disease can be diagnosed through physical examination. All fish in the pond or aquarium that may be affected need to be evaluated. If there are visible bubbles on the fish’s skin or fins, aspiration will be carried out with a syringe with a fine needle to determine whether the bubbles are air or clear liquid.
- X – ray examination: To determine whether there are internal bubbles in the fish, an X – ray radiograph may be taken of the fish. This process usually requires sedating the fish to obtain a clear image.
- Gill tissue examination: Bubbles may also be present in the gill tissue. This can be detected by microscopic examination of a wet mount of a gill biopsy, which is a common diagnostic method for aquatic organisms.
How to Treat Fish Gas Bubble Disease
- Remove bubbles: Veterinarians usually use a very small needle and syringe to aspirate and remove the bubbles.
- Antibiotic treatment: Antibiotic treatment is a common adjunct in the treatment protocol for gas bubble disease.
- Identify and eliminate the cause: The cause of the microbubbles in the pond or aquarium must be identified and eliminated. Check the aeration, water pumps, and water flow back into the aquarium; look for tiny bubbles on plants, decorations, or the aquarium walls; temporarily turn off the filter to observe whether bubbles are still forming to determine if the filter is the cause of gas supersaturation; evaluate all the animals in the aquarium or pond to ensure that all symptomatic fish are effectively treated.
Once the source of gas supersaturation in the water is identified and corrected, the microbubbles will naturally dissipate over time. Gently stirring the water helps to remove excess gas from the water, and slightly lowering the water temperature also helps, as colder water can naturally hold more dissolved gas, but do not cool the water by more than a few degrees each time.
Prognosis of Fish Gas Bubble Disease
If the supersaturation state in the water is eliminated, the gas will naturally dissipate from the fish’s body, and the bubbles will disappear. However, if bubbles have already formed in the fish’s brain, heart, kidneys, or other organs, the disease may be fatal before it resolves. Even if the supersaturation state is corrected, fish with bubbles in their fin capillaries may lose fin tissue due to blocked blood flow to the fins. Early detection and treatment are the keys to the survival and recovery of fish.
How to Prevent Fish Gas Bubble Disease
- Check equipment: Ensure that all plumbing and filtration components are properly connected and sealed.
- Control water level: Keep the water level appropriate and top up the water in a timely manner when necessary. Record the water change schedule to detect water leaks early.
- Control water temperature: Always check the water temperature when changing water, and make the temperature of the newly added water the same as or within a few degrees of the original water temperature.
- Monitor bubbles: Monitor whether there are microbubbles in the water similar to those in champagne. There should be no large number of bubbles forming on the aquarium glass, decorations, or the walls of the pond.
By understanding the causes, symptoms, effective treatment and prevention methods of fish gas bubble disease, we can better protect the health of fish and create a safe and suitable living environment for them. Whether you are a professional aquaculturist or an ordinary ornamental fish enthusiast, you should attach importance to this disease and take proactive measures to deal with it.
