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The use of salt in the aquarium is undoubtedly a controversial topic. Should we use it, how do we use it and when should we use it? On the one hand, aquarium salt has a group of fans and on the other hand there are many detractors who definitely do not recommend its use in freshwater tanks. As usual, the truth lies somewhere in between. Below we describe the potential risks and benefits of using salt in your aquarium that may help you take a stand on this issue.

Why use aquarium salt?

Salt producers ensure that keeping the water in your freshwater aquarium lightly salted is beneficial to the health of your fish, preventing parasitic infections and helping to treat disease. What's more, there are many arguments that it reduces stress on fish by lowering the osmotic pressure in the water and reducing the absorption of nitrates. So let's take a closer look at the benefits above.

Parasitic or fungal infections

Salt is a very effective remedy against most infections caused by parasites and fungi - however, in this case, a short treatment bath in a more concentrated solution is more effective than adding a small amount of salt directly to the tank. Some fishers use small amounts of salt in their main aquarium to keep parasites at bay. Does it make sense? Yes and no. On the one hand, adding salt in small amounts may increase the production of protective mucus in fish, thereby enhancing their natural resistance to possible infections. On the other hand, many parasites and fungi tolerate such low salt concentrations well, so it is not a very strong protective barrier.

Osmoregulation

Osmoregulation is a group of biological processes that essentially regulate the concentration and volume of organic compounds and electrolytes in body fluids. It is based on the phenomenon of osmosis - the semi-permeable membrane through which water attempts to permeate from a lower concentration to a higher concentration. Freshwater fish naturally have higher salt concentrations than the water they inhabit, which means they are constantly releasing salt from their bodies into the water in their tanks and absorbing water. Visually, it can be said that it looks as if the water from the aquarium try used to dilute the fish. In order to balance the osmotic process and maintain the proper concentration of mineral salts, the fish must re-extract them from the water through their gills.

In healthy fish in good condition, these processes are always normal and usually do not require any support. However, under the influence of stress, disease, or during recovery, a fish may not be able to take up enough salt from the water, resulting in osmotic shock.

Proponents of salting aquariums claim that by gently increasing the salt level in the aquarium when fish are in an adverse state (stressed, in treatment), they can be helped to recover because their cells don't have to work as hard during osmoregulation.

There are no clear guidelines on what salt concentration to use to help osmoregulate fish. Advice from practitioners on aquarium forums is very varied, ranging from 1,200 level teaspoons per 1 liter of water to 4 level teaspoons per 1 liter of water! Such recommendations should be treated with great caution, read the manufacturer's recommendations first - and treat them with care. It is best to use half of the manufacturer's recommended dose on the first day, watch the fish carefully and only after ensuring that they tolerate the change in salinity well - after a day or two - add the second part of the recommended dose.

Nitrate poisoning

Nitrate levels can increase if there are not enough beneficial bacteria in the aquarium to absorb the toxic by-products of fish feces. This can happen if the tank is immature or inadequately filtered. A quick addition of salt will help create a natural barrier where chloride ions prevent the fish from absorbing nitrates. In this case, there must be 30 times more chloride ions in the water than nitrate ions. It is best to perform a nitrate tank test and adjust the dosage accordingly.

Which salts are used in the aquarium?

We will highlight the three most popular types here:

- Non-Iodized Salt - In theory, it is pure sodium chloride (NaCl). The lack of additional ingredients (as well as the low price) means that many aquarists will buy this "common" salt and use it successfully in their aquariums.

- Sea salt - the composition is much more complex than table salt. In addition to sodium chloride, it usually contains many different minerals such as calcium, magnesium, potassium and zinc. The composition of sea salt from different sediments may differ significantly from each other. Sea salt is only suitable for aquariums with marine fish and invertebrates, although some people recommend using it in therapeutic baths as well.

- Freshwater aquarium aquarium salt is a very popular product and is available at almost every pet store. Freshwater aquarium salt is usually made from evaporated seawater. It is a product designed for freshwater aquariums and therefore does not contain any additives that are harmful to fish, such as iodine or anti-caking agents. Keep in mind that aquarium salt from different manufacturers may have different chemical compositions. Therefore, when changing from one product to another, use caution and always follow the manufacturer's recommendations. Often in stores you can buy aquarium salt with "extra" additives such as aloe vera or oak bark.

Is salt good for freshwater fish?

The correct use of aquarium salt can have a very positive effect on fish and in some cases can even save their lives. Overuse of the same salt can kill half of the aquarium in a short time. Again: this measure deserves great care. What matters is not only the type and dose of salt, but also the species of fish - because they do not react to salt in exactly the same way. In general, we can accept the rule (although there are exceptions to all rules) that the more acidic and soft water a given species needs, the less it tolerates the addition of salt. Fish that do not respond well to salt include catfish, pleco, otos, discus, and koi. Goldfish, peacockfish and most African cichlids respond very well to the addition of salt to the aquarium.

Is salt good for plants and other aquarium inhabitants?

In this case, the answer is definitely no . Most freshwater plants respond very unfavorably to salt, and even small additions can result in massive plant death. So, it's best to avoid salt in a tank with live plants.

Salt is also deadly to algae. If we suffer from their excesses, salt treatments can be effective against them. However, if we care about the presence of algae in the aquarium, it is best not to add salt.

All invertebrates, especially snails, are also very sensitive to salt. They should be captured and transferred to another tank before adding salt to the water.

How can I safely use salt in my freshwater aquarium?

First, be careful. If you are adding salt for the first time - use half the dosage recommended by the manufacturer and after two days (if the fish respond well), add the other half. Also, be ready to intervene quickly if the fish begins to exhibit disturbing behavior. The only way to save yourself in this situation is to catch the fish and replace the water completely.

Never add salt directly to the aquarium; instead, completely dissolve the salt in some of the water and add it slowly, waiting for the solution to be evenly distributed throughout the aquarium.

Remember that salt does not evaporate and is not removed by the filter! Salt added to the tank will stay in there once. The only way to remove it is to change the water. Therefore, there is no need to refill the aquarium with salt except for a partial water change, and here we also add proportionally as much salt as the removed water, i.e. if we change 30% of the water - we add 30% of the entire tank's salt dose.

You should also pay attention to water evaporation - less water in the aquarium means higher salt concentration. The water should be filled up as soon as possible, without adding salt to it, of course.

To summarize: adding salt is controversial because of the high risks associated with its misuse. However, if used carefully and in moderation, it can have a very beneficial effect on the health and condition of the fish, and many keepers are very fond of adding salt to their freshwater aquariums. It is necessary to gather as much information as possible about the fish you are breeding and their sensitivity to salt before making a decision. Remember also to add salt to your tank, starting with small doses. Most importantly: salt kills plants, so if you intend to use it, only use it for therapeutic purposes during quarantine.