Fish in the pond gasping for air | Goldfish swim above

Although fish live in water, they need oxygen to survive. It filters this oxygen out of the water. This “filter system” is located in the gills of the animals, which absorb water through their mouths. The water then passes through the gills, where they pass through the gill arches, which are heavily supplied with blood. Oxygen can be absorbed by the fish via the blood-supplied gill skin. The water and carbon dioxide are “exhaled” through the gill cover.

Although there is significantly less oxygen in the water than in the air people breathe, it is enough for the fish to be able to filter enough air out of it. The prerequisite for this is that there is sufficient oxygen in the water. It is therefore particularly important in a biotope with fish to ensure a natural balance, because just as too little oxygen can damage the animals, too much oxygen is also problematic for the ecology in the pond. If the oxygen level is too low, they are at risk of suffocation.

Heed warning signs

There are many causes that ensure a reduced oxygen content in the water. However, it is important that gardeners recognize the warning signs and take swift action to protect the animals. One of the signs that something is wrong is when the fish are increasing, swimming to the top. Staying close to the water surface is a risk for the animals, because there they are easier prey for predators, which is why they are only up there in an emergency.

Another warning sign is the fish gasping for air. Due to the low oxygen content in the water, they have to absorb water at a higher frequency. This looks like gasping, rapidly sucking in and releasing water.

Reasons for lack of oxygen

Especially in summer, the risk of an oxygen deficiency is high. On the one hand, this can be due to the ecology in the water, on the other hand, it can also be due to the animals themselves, which may be suffering from an illness.

Problems with the water:

• high temperature, causing too little oxygen to be dissolved in the water
• too few plants in the pond that produce oxygen
• too many fish in the pond
• rot in the ground
• Filter does not work, which means that the flow is too low

Diseases that cause gasping:

• kiemenwurmer
• Ichthyophthiriose
• velvet sickness
• Epitheliocystis
• Chemical burns due to incorrect pH value

immediate measures

At the first sign that there is a problem, you must react immediately, otherwise this can quickly lead to the death of the animals. If there are problems with the water, the oxygen content must be increased immediately. This can be achieved, for example, by using a membrane pump to ensure additional water movement and more oxygen in the water.

The oxygen content is also quickly increased by feeding tap water into the pond. However, these are only short-term first-aid measures to increase the oxygen content in the water. In the long term, the cause of the insufficient oxygen content must be eliminated.

However, if only a few animals have breathing problems, it may be a disease. Animals that show signs that they are having difficulty breathing should be separated in the first step so that there is no further infection. Then you have to clarify with the veterinarian which disease is present and, if necessary, take countermeasures.

Make long-term provisions

So that the oxygen concentration does not drop again, it is important to improve the climate in the water in the long term. Especially if the oxygen level regularly drops to a critical level, you should consider purchasing an oxidizer. This works completely without electricity and is set up in the shallow water zone at a depth of around 60 cm. The oxidizer contains a cartridge with hydrogen peroxide, which gradually breaks down into oxygen and water. This makes it possible to provide oxygen, especially in ponds that have problems due to solar radiation and, as a result, high water temperatures.

improve water climate

However, devices are not absolutely necessary for a sustainable improvement of the pond climate. One possibility is to reduce the fish population. A single goldfish or even a very small koi requires 1,000 liters of water per fish. If the pond is approx. 10 m³, a stocking of up to new fish of this size is possible.

Especially when new fish appear, either the pond area has to be enlarged or new quarters have to be found for the fish. When designing the pond itself, the commercially available plastic tubs are very convenient, but they are not suitable for fish. Regardless of the size of the tank, they do not provide the pond climate that fish would need to thrive in it. Natural ponds or ponds that are tiled with natural stones offer an ideal climate.

the shade

Shading is particularly important in summer because it reduces the effort required to keep the oxygen balance at a healthy level. Suitable border planting can provide shade. Chinese reeds or other grasses with height growth are suitable for this. Alternatively, you can plant conifers in suitable places, the height and width of which can also be controlled by pruning.

Plants not only provide enough shade at the edge of the pond so that the water does not get so hot that the fish gasp for air, but also aquatic plants offer the animals protection. Ideal for this are water lilies, whose leaves should cover around a third of the water surface.

Aquatic plants as oxygen donors

Aquatic plants not only provide shade, they are also important oxygen producers in the pond. Examples of important oxygen suppliers are:

• waterweed
• Hornkraut
• thousand leaf
• pike weed
• buckbean

If the fish are in the pond all year round, plants should be chosen that are frost-resistant. As a result, the animals have enough air available even in winter. Especially then, an oxygen supply can be dangerous, because if there is a layer of ice, the fish have no opportunity to swim up to get air.

However, aquatic plants should be used with care, because they are one of the reasons why rot can develop in the pond and, in turn, a lack of oxygen. Waters with fish and plants must therefore be cleaned regularly. The dead plant parts cannot rot on the ground and provide nitrogen in the water.

Feed properly

One problem causing the animals to come up for air is excess food in the water. The food that the animals don’t eat sinks to the bottom and begins to rot there. As with too many plant residues on the pond floor, this leads to rot and thus to a high nitrogen content.

Therefore, you should not only feed them according to their needs, but also use suitable fish food. Above all, incorrect feeding, for example with leftover bread, can not only lead to the water tipping over, but also attract pests that may also be dangerous to the fish.

Regular controll

Regular checks are an important factor in ensuring that the animals remain healthy and find a suitable living environment. As with dogs, cats or hamsters, you have to check on the fish every day. This has the advantage that problems with the biotope can be recognized early. This can also be factors such as autumn leaves that fall into the water and promote the formation of sludge there.

Not only the habitat of the fish has to be checked, but also the animals themselves. With a daily check, changes in behavior are quickly noticed, such as when they come up for air. This is a sure indication that something is wrong and the cause can be investigated immediately.

Cleanliness is also an important issue in the pond. In the case of animals in cages, the cage is cleaned regularly and the litter in the litter box is also changed regularly. Exactly this hygiene is also necessary for fish, even if the effort is greater here. For this, a basic cleaning of the pool often only has to be carried out once a year.

Especially with very expensive fish, additional effort is often made to ensure animal health. Koi owners often do additional water testing to check for nitrate and ammonia levels.