Unwanted guests in the aquarium

All aquarium owners envision a vibrant aquatic ecosystem with lush plants and colorful fish. Even the best-maintained tanks, though, are susceptible to unwanted visitors. These invaders can be anything from dangerous parasites to bothersome pests, and they’re all dangerous for the equilibrium and well-being of your aquatic ecosystem.

Keeping an aquarium healthy requires quickly recognizing and removing these unwanted guests. From ugly algae to microscopic, bothersome creatures, knowing what you’re

Water burros Asellus

Water lice, or water burros Asellus, are aquatic crustaceans. They resemble woodlice in certain ways because they are related to them. They live in inaccessible crevices in ornamental items and the filter, and they can be added to the aquarium with live food or as live food. Although they can serve as intermediate hosts for acanthocephalans, or spiny-headed worms, they do not directly harm fish. There’s no reason to be concerned about this as these worms don’t usually infect aquarium fish. On the other hand, a high concentration of Asellus water burros suggests that the aquarium is heavily contaminated with organic matter, to which these animals also contribute.

Polychaete worms

These are annelids from the Naididae family, reaching 2 cm in length. They are characterized by the presence of bristles (it is possible that these bristles are what make them inedible to fish). Most often, these are white or pink worms that reproduce by budding or laying eggs. They can be brought into the aquarium along with plants, in the shells of aquatic snails, or with water in which live food caught in the wild was carried. In an aquarium, they can live in the soil layer or on its surface, feeding on detritus. Therefore, their presence in significant quantities is an indicator of poor aquarium hygiene and the danger that fish are exposed to due to pollution. These worms themselves are harmless. Improving aquarium hygiene will help control their numbers and will benefit the fish, as it will improve their living conditions.

Algae

Lower aquatic plants called algae can cling to underwater surfaces or swim freely, depending on the species. They can come in a variety of forms and hues, including green, brown, red, gray, and yellowish. They can have a variety of appearances, such as fluffy tufts, a carpet that resembles moss, or long, fibrous tufts (like the mud we see in ponds during the summer). The so-called blue-green algae are not the same as true algae; they are categorized as cyanobacteria in science.

Algae are inevitable wherever water, nutrients and light are present at the same time. All three elements are present in every aquarium, so the aquarist must learn to accept that algae are a natural and inevitable part of the aquarium ecosystem. In an aquarium, as in nature, algae provide a number of benefits. They are a natural food source for some herbivorous fish. Together with the microorganisms that live on them, they are an excellent source of first food for fry. They reduce the amount of nitrates in the water, which they use as food. Algae also give completely bare decorative objects, such as stones, a more natural look, since in natural bodies of water, stones are usually covered with algae. If algae grow too rapidly, this is a warning of possible problems with water quality.

Algae of very different kinds will be found in different aquariums. This depends in part on the aquarium’s lighting, where bright lighting promotes the growth of bright green algae and low lighting favors brown slimy algae.

Algae that cover plant leaves and aquarium glass are thought to be especially problematic. Nonetheless, using a scraper or magnetic glass cleaner makes it simple to maintain the cleanliness of an aquarium’s front glass. You can leave algae on the aquarium’s glass that isn’t being viewed. The algae will help remove nitrates and give the fish food if they stay there. An algae-covered back glass is a bonus if the aquarist enjoys taking pictures since it keeps light from reflecting off the flash on the camera.

It is quite common for aquatic plants to have their old leaves covered in algae in the natural world. These leaves die off and are successively replaced by new leaves. When algae on aquarium plants cause problems, it’s usually because the higher plants aren’t growing quickly enough or the algae are growing too quickly. In an effort to control the algae, aquarists frequently make the error of dimming the aquarium’s lighting or extending its duration. However, they are worsening the issue by stifling the growth of taller plants! Algae are impeded in their growth by healthy plants that compete with them for the few nutrients available.

If you have to remove algae from the viewing glasses every few days, it means that the algae are growing too fast. This happens when there is an excess of nutrients. Algae is becoming a real problem – this is a sign of high nitrate or phosphate levels. This, in turn, can be caused by too high a dose of aquarium fertilizers designed to accelerate plant growth, but more often it is an indicator of poor aquarium maintenance – its overcrowding, overfeeding of fish, insufficient volumes of water changes, excessive amounts of waste, or a combination of these factors. Tap water used for partial water changes in an aquarium may contain too much nitrates and other substances that serve as food for algae. So it is not the algae themselves, but the cause of their excessive growth, whatever it may be, that requires attention! Otherwise, the health of the fish will be adversely affected – due to the pollution of the aquarium, and not due to the algae themselves!

Sometimes the amount of invisible free-floating algae grows to such an extent that the water takes on the appearance of pea soup. This is what’s known as the "algae bloom." This phenomenon can be seen in summertime ponds, but it can also happen in an aquarium if it is exposed to direct sunlight for an extended period of time. Furthermore, there is a high level of organic pollution indicated by this issue.

Although there are special aquarium products for destroying algae on the market, the solution to this problem, too easy in appearance, is not really a solution. The death and decomposition of large amounts of algae can overload the filtration system and further aggravate the pollution problem that caused the algae to grow in the first place. Even if this does not happen, the dead algae will further increase the organic matter content of the aquarium. So when algae repopulate the aquarium (and they inevitably will), then the problem will be even more acute than the first time. Repeated use of chemicals to combat algae and bio-overload will almost certainly have an adverse effect on fish and higher vegetation. So it is best to identify and eliminate the cause of the excess algae, and if their growth is normal, consider them friends rather than enemies.

Some fish can be used to prevent algae growth because they are known to be "algae eaters," such as Gyrinocheilus aymonieri and some catfish with a sucker mouth. This approach does not, however, remove the requirement to keep the aquarium’s organic waste concentration low.

Copepods

Copepods are tiny crustaceans found in water. Fish cannot harm most of them. Certain species that are free-living, like cyclops, are utilized as live food. In addition, certain copepod species have parasitic forms on fish.

Free-living harmless copepods are usually translucent and reach 3 mm in length. They move in short jumps, but can also lie on underwater surfaces, including on aquarium glass, where they are introduced either intentionally (as live food) or accidentally (on plants). Few manage to survive in an aquarium for a long time – for most fish, this is a real delicacy. However, large fish do not pay attention to them – after all, they are too small and should not be eaten. Thus, the only way for a free-living copepod to infest an aquarium is if the fish do not eat them, either because they are unsuitable food or because the fish are so unwell that they have lost interest in even such a tempting food source. This can be due to environmental pollution (heavy organic load). If copepods start to multiply in an aquarium, then there is organic pollution.

The fish will gladly find a solution on their own if the issue that gave rise to this behavior is resolved.

Cyanobacteria

This is a group of microorganisms that causes the growth of a substance resembling algae. Aquarists call it "blue-green algae". The appearance of such "algae" is associated with high levels of nitrates and phosphates. True, not all aquariums with a large amount of organic waste are filled with these "algae". They can cover all decorative objects in the aquarium, including the substrate, with a slimy bluish-green coating overnight. There is no evidence that they cause direct harm to adult fish (but they can be harmed by poor water quality, which has caused the rapid proliferation of cyanobacteria). However, these “algae” can very quickly cover and suffocate fry lying on the substrate or decorative objects. In addition, they can completely cover plants and destroy them.

Eliminating blue-green algae completely is a very challenging task. Later on, they can start reproducing quickly once more with even the smallest decline in the quality of the water. Reducing the amount of organic waste and filtering out as much of this green mass as possible during each partial water change is the only way out. Regretfully, fish find blue-green algae to be utterly inappealing. None of the writers of this article can personally verify the rumored feeding source of these algae—ground snails Melania sand. Furthermore, the cyanobacteria themselves are just as inconvenient as these snails.

Hydra

Sea anemones’ freshwater relatives are these tiny coelenterates. They range in length from 2 mm to 2 cm (tentacles included). They resemble stalks, with one end attached to a hard base and the other topped with tentacles. These characteristics all help you to identify them with clarity. Yes, occasionally they get smaller and resemble tiny jelly balls. They can be cream, gray, or light brown in color. There exist hydras with a pleasing green hue that can be mistaken for algae.

A hydra (Hydra) may occasionally be found in an aquarium with live food or ornamental natural objects. Afterwards, they focus on a few items or the glass of the aquarium and depict more fascinating objects that are nearly as endearing as the aquarium’s primary inhabitants.

Although hydras do not harm mature fish, they can capture fry and other small fish as well as tiny bits of fish food. Occasionally, their population grows to the point where they become actual pests. Similar to numerous other pests, they signify issues related to aquarium maintenance.

To completely destroy hydras, you have to completely empty the aquarium, scrape all its surfaces, wash the gravel, decorative objects and underwater equipment in a hot 2-5% saline solution at a temperature above 40 ° C. If the aquarium is planted, then these plants are unlikely to respond well to cleaning in hot salt water! Therefore, it is better to use an alternative method, which consists in removing all fish from the aquarium (and also snails, if they are desired inhabitants of the aquarium) to some temporary room and increasing the water temperature in the aquarium to 42 ° C for half an hour. During the heating process, the filler that serves as a substrate for bacteria should be removed from the internal filters, but it is better to leave the filters in place because hydras attach to their surface. External filters should be turned off, but not for more than an hour, otherwise the bacterial population may die due to lack of oxygen. Then the aquarium should be allowed to cool down to normal temperature or cool it by partially changing the water, adding cold water. After this, you can start the fish again (as well as snails) and restore filtration.

Table salt can be dissolved in water to control the hydra population in a fish-filled aquarium; the result should be a 0.5% saline solution. After about a week, this solution should be kept in place. After that, progressively remove the salt by doing frequent partial water changes. Only fish that can withstand this level of salinity well can use this technique. If not, you will need to remove rocks and other hard ornamental items from the aquarium and treat them in hot salt water, as well as clean the glass of the aquarium on a regular basis and filter out the separated hydras.

Certain types of fish consume hydras, particularly gourami and young cichlids that "graze" on rocks. Consequently, if these fish are a good fit for the aquarium in question, they can be used to manage the hydra population.

Leechs

Leeches are seen freely floating in the water or resting on ornamental items after being inadvertently brought into the aquarium. Certain leech species have representatives that live as parasites on fish.

Roundworms (nematodes)

This is a broad category of roundworms, or worms that resemble threads. There are parasitic and free-living species among them. Red-brown worms that are 1-3 cm long and have an unsegmented body are known as non-parasitic nematodes. They occasionally overflow the biological filter and substrate. They are completely harmless and can be added to the aquarium along with live food. If they become excessively numerous, it means that the fish’s diet and aquarium hygiene need to be changed. To cut down on nematodes, these enhancements are the only things required.

Shell crustaceans

Shell crustaceans Ostracoda are bean-shaped crustaceans, reaching 4 mm in length. Sometimes you can see them scurrying around on the substrate, like tiny moving spots. These creatures are yellowish or black-brown in color. They attach their eggs to plants, so they can be accidentally introduced into the aquarium along with plants, as well as with live food. They are found in small numbers in aquariums, but if the hygiene of the aquarium leaves much to be desired, they can begin to multiply rapidly and become a real disaster. So, although shellfish are harmless, their presence indicates that there are problems with the environment or with the fish"s diet. These problems can have an adverse effect on the fish. Improving the care of the aquarium is a solution to both problems at the same time. It allows you to control the population of these animals and eliminate the causes of their rapid reproduction.

Algae, pests, and illnesses are examples of unwanted visitors that can upset the harmony and beauty of your underwater habitat. Maintaining a healthy and vibrant aquarium depends on being able to recognize these invaders early on and comprehending how they impact your fish and plants. Maintaining a clean and vibrant aquatic environment can be achieved through effective prevention and management techniques.

Planaria

Because they are mistaken for parasites like leeches, harmless non-parasitic flatworms called planaria frequently instill fear in the hearts of aquarium keepers. They are typically creamy white, gray, or brown in color, and range in length from 2 to 10 mm. When placed on aquarium glass, light planaria appear translucent, while dark planaria resemble tiny slugs. A V-shaped head and a slow, gliding motion across the aquarium’s surfaces are two of its distinguishing characteristics.

Unintentionally adding planaria, aquatic plants, or live food to the aquarium is possible. Planaria may live in the substrate or on the surface of the aquarium in a tiny, imperceptible population. Occasionally, their population grows to an unmanageable size, allowing them to freely swim in the water or crawl on the aquarium’s front glass. Such quick reproduction is a sign that the fish are being overfed. Planaria eat uneaten food, which causes their population to grow explosively. If the fish’s health has been harmed by overfeeding, it is imperative to evaluate their feeding schedule and treat the contaminated water.

Planaria is a common issue in situations where large fish consume food that breaks down in their mouths. Following this, a massive shower of food particles shoots from the gills and descends to the bottom. Large fish won’t be interested in these particles because they are too small. In these situations, the true issue may lie in the type of food rather than its quantity. Altering the fish’s diet or keeping fish in the aquarium who dig in the substrate and clear out anything that falls from above are two potential solutions.

Planaria are eaten by certain fish species, like gourami, which helps to regulate their population. Nevertheless, this control measure does not eliminate other risks, specifically food-related pollution. As such, it is not appropriate to regard it as the best way to solve the issue.

Snails

In order to use aquatic snails as "cleaners" and remove food scraps from the aquarium, some aquarists purposefully release them into the tank. Snails can accidentally wind up in aquariums; they usually land there on plants. However, once the snails are in the aquarium, it is extremely difficult to take them out if they turn out to be unwanted. This is particularly true for Melania tuberculata, a viviparous snail. These snails are sedentary, meaning they can reproduce in large quantities without the aquarist noticing. They live in the ground.

A lot of snails in the aquarium is a sign that something is wrong. Snails need to consume oxygen and produce organic waste in addition to finding enough organic matter to feed on in order to survive. A few snails consume fish eggs. Numerous parasites, for which they serve as intermediate hosts, can be introduced into aquariums by snails that are harvested from decorative ponds or captured in the wild.

By routinely eliminating every snail that is visible, populations of snails can be maintained within manageable bounds. You could, for instance, filter them or gather them with a net. Big ones can be manually captured one at a time. Since most snails are active at night, it is preferable to remove snails from the aquarium after the lights have been turned off. At night, bottom snails depart in search of food on ornamental items and aquarium glass.

There are special means for the destruction of snails on sale, but their use is undesirable in aquariums inhabited by fish. Most of these snail killers contain copper, which is toxic to fish, so overdosing can be fatal. Snail carcasses can make a huge mess in an aquarium, especially where sand snails are the main problem. Even if you apply this chemical at night, you will likely still end up with countless dead snails in the substrate. If you are still convinced that you need to use this product to kill sand snails, the fish should be moved to another room. After this, the aquarium should be treated, then thoroughly cleaned and reinstalled with new substrate.

It is acceptable to treat aquarium plants with a snail killer prior to planting them in order to prevent unintentionally introducing snails. Keep in mind that small snails might go unnoticed if you examine the plants closely. Avoid purchasing fish from aquariums containing sand melanias. Tiny newborn snails can very easily become "stowaways" in nets, fish carrier bags, siphon tubes, and other equipment, so if they have gotten into any of your tanks, keep it in quarantine until you have completely eradicated them.

Unwanted Guest	Description
Amoebas	Single-celled organisms that can cause infections in fish.
Algae	Excessive growth can lead to poor water quality and reduced oxygen levels.
Snails	Can overpopulate quickly and consume plants and food meant for fish.
Parasitic Worms	May infest fish and cause health issues.
Invasive Plants	Can outgrow other plants and disrupt the balance of the aquarium.

It can be difficult to deal with unwanted visitors in your aquarium, but you can maintain the health and well-being of your aquatic ecosystem by taking the appropriate measures. Preventing and controlling these intruders requires vigilante maintenance. You can identify possible problems early on by monitoring your fish and plants, keeping a careful check on the water quality, and doing routine cleanings.

When unwelcome visitors such as algae, pests, or illness appear, take prompt action to resolve the issue. You can help restore balance and safeguard your aquatic life by eliminating pollutants, modifying the conditions in your aquarium, and applying the proper treatments. Keep in mind that prevention is always preferable to treatment, so devoting time to appropriate maintenance and care will spare you from more serious problems in the future.

In the end, keeping an aquarium healthy calls for perseverance and commitment. You can give your fish and plants a stable and comfortable environment by keeping up with common problems and solutions. Your aquarium will stay a lovely and peaceful place for many years to come with regular maintenance.

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