Aquarium pests / 26 types / With videos and photos

It happens that aquariums are invaded by pests! And these “guests” cause great concern among aquarists, although most of them are inherently harmless. But sometimes these fears are not unfounded since the presence of these organisms in large numbers in the aquarium is a sign of deterioration of the fish habitat. In addition, this indicates the carelessness of the aquarist to some details: low-quality live food is used (in which these organisms may be present), or decorative material from natural reservoirs that have not been properly processed is used.

Such pests are unpleasant to look at and create certain inconveniences. Although they do not directly harm fish, their presence is a warning signal and cannot be ignored.

Acroloxus

Ham-nyom-nyamm: Acroloxus Lacustris eating
Small snails up to 5 mm in size do no harm, except for the stress that they cause by their presence on a perfectionist aquarist. If there are few snails, you don’t need to fight them, if there are a lot of them, as you said above, you are overfeeding fish, review your approach to feeding pets. We are convinced that the best method of fighting snails is Anentome helena, get some predatory snail helena and very soon the acroluxus will disappear from your aquarium. You can use chemicals, but be careful if you contain other, more “noble” snails: apple snail, Neritina, Tylomelania, etc. they will also suffer from chemistry. You can also arrange snail traps, for example, they crawl out to feast on a piece of cucumber, carrot, banana skin. You only have to get a treat in the morning and throw snails from it after. This statement is true for all snails except predatory ones.

Aulophorus

Aulophorus furcatus
Worms up to 2 cm long with a thin body (0.2 mm), usually they can be seen on glass, less often in the water column, the worms swim strongly curving with their whole body. You can bring Aulophorus into the aquarium from a natural reservoir. For aquarium fish, they are a treat, so aulophorus accidentally entered into the aquarium is unlikely to live there for long. The culture of these worms is even specially bred for feeding. It is eaten by all kinds of fish. However, there is an opinion that it is not worth feeding fish with this worm all the time because this can cause obesity.

Water hoglouse (Asellus aquaticus)

Water hoglouse (Asellus aquaticus)

A representative of the order of isopod crustaceans, ranging in size from 1 to 2 cm, can be brought from standing, slightly marshy ponds, where decaying organic matter eats from the bottom. It is quite simple to recognize a water hoglouse: by two pairs of antennae. One of the pairs is short, the other is almost as long as the body of a crustacean. The eyes are faceted, the body is clearly segmented into 8 segments and covered with a thin layer of chitin. Safe for fish, an excellent fodder facility.

Water mites (Hydrachnidae)

A guide to freshwater inverts - Water mites
The mites are 2-3 mm in size, from yellow to bright orange, some subspecies have a pattern on the body. In life, there are several metamorphoses: larva. They parasitize on aquatic insects and crustaceans, for example, on all familiar Daphnia and Cyclops. They are safe for fish, but at the same time practically inedible.

Hydra

hydra

The first truly dangerous uninvited aquarium guest on our list. Remember the myth of the Lernean Hydra, it immediately becomes creepy, right?

Coelenterata animals ranging in size from 2 to 20 mm. This name speaks for itself, the hydra is actually a digestive system with the ability to reproduce. At one end, it is attached to some object, for example, a stone, and catches prey with its tentacles. Eating fry of a fish, for a hydra, costs nothing. It can also hurt adult fish by damaging them with stinging cells located on the tentacles. Hydra has two ways of reproduction: division (budding) and ordinary sexual. That is, if you cut the hydra in two, you really will get two hydras in a myth. Hydras are brought into the aquarium mainly with natural decorative objects that have been poorly processed.

How to get rid of hydra in an aquarium?

It all depends on the size of the hydra population, and the species composition of your aquarium. Gourami, as well as other Anabantoidei: Siamese fighting fish, Paradise fish, Dwarf gourami, eat hydra and can cope with a small population themselves. If there are a lot of hydras, in our opinion, the best way out is to resort to modern achievements in aquaristics, special preparations against hydras, such are in the product line of all well-known manufacturers of aquarium chemistry, most often such preparations are made on the basis of heavy metals, for example, copper. but many years of experience and numerous trials have allowed scientists to create drugs that can kill hydra and not harm the fish.

This is how hydras look in the aquarium:

Freshwater Hydra in Planted Betta Aquarium
There are other ways, one of them is to add salt to the water, calculating the dose so that a 0.5% saline solution is obtained in the aquarium. This inhibits the growth of the hydra population, do you remember what happens to various slugs if you sprinkle them with salt? But keep in mind that before using this method, you need to make sure that all other inhabitants of your aquarium tolerate a similar level of salinity.

And finally, 2 very extreme methods: temporarily relocate all fish, and raise the temperature in the aquarium above 42 degrees Celsius for an hour, the hydra should die, but keep in mind that not all beneficial bacteria tolerate such a temperature, and such an aquarium bath, with with a high degree of probability it will strike the biological balance in it.

The latter method can be compared to nuclear bombing, it should be resorted to when absolutely nothing helps – this is a complete restart of the aquarium, with draining all the water, flushing the walls, boiling the soil and decorations and other horrors.

Daphnia 

Daphnia

Small crustacean (size from 0.2 to 6 mm) of the genus planktonic crustaceans. Crustaceans move in long leaps, for which they received the second name – the water flea. It is actively cultivated by aquarists as food for fish, and can also bring other benefits to the aquarium: bacteria and unicellular algae serve as the basis for daphnia’s nutrition, thereby daphnia can prevent blooming in the aquarium.

Infusoria Peritricha

Unknown peritricha
Small protozoa a few millimeters in size, places where ciliates are very much visible with the naked eye: white bloom appears on stones, plants, snags, water becomes cloudy. Ciliates always settle in large numbers in the aquarium, which has just begun to start, and the biobalance is adjusted, as soon as the biobalance in the aquarium is fully adjusted, and the ciliates eat the excess bacteria – they will disappear on their own, they simply will not have enough nutrition, plus the fish that you populate in the aquarium will also not mind eating these protozoa.

Infusoria Vorticella

Infusoria Vorticella

Another type of ciliates. They are motionless, it is impossible to see a single infusoria with the naked eye, its size is slightly more than 0.2 mm. They often settle on the shells of mollusks, sometimes there is such a phenomenon as “false fungal disease of shrimp” – the overgrowth of shells by large colonies of Vorticella. In this case, Vorticella can be harmful by getting into the respiratory tract of the shrimp, thereby causing suffocation. If there are so many Vorticella that there are problems with them – there are too many bacteria in the water, the bio balance is seriously disturbed or simply absent – start adjusting it.

Infusoria Stentor

Stentor eating a rotifer alive/ Инфузория Трубач vs Коловратки
One of the largest ciliates, they can be seen without even resorting to a magnifying glass, the body is a long stalk with an extension at the end – just like a tube in miniature. Some subspecies are brightly colored, which makes them even more visible to the human eye. For a long time, they can be motionless, attached to any surface, but they can also float freely. At the slightest danger, they shrink sharply, take a spherical shape, trying to fall into the ground and mix with it. Single ciliates brought into the aquarium with water or plants are not dangerous, but if there are too many of them, the problem is the same: the lack of bio-balance and the growth of the protozoa population is only an indicator.

Zoothamnium arbuscula

Microscopic ciliates, the maximum size of one individual is 60 micrometers. They live on plants in colonies, in case of danger, the entire colony shrinks, forming a small ball.

Snail Planorbidae

It is safe to say that these small brown to red colored snails have been encountered in their practice by 100% of aquarists. Most often they are brought in in the form of eggs with plants, or decorations that are bought. These snails are extremely fertile, and if favorable conditions are created for them: excess food, harder water, not very clean water, and algae on glass – you risk getting a real invasion of these snails. In general, they are harmless, but when they are located throughout the aquarium in large clusters, it is extremely unaesthetic, will you agree?

Snail Planorbidae

The methods of struggle are simple – no overfeeding, clean water. If the coils have multiplied, you can remove them manually, you can prepare various traps for them, the most primitive one is a cucumber, several dozen individuals gather on a half of a cucumber overnight. The best and most natural, in my opinion, method of fighting, as well as with the Acroluxus snails, is Helena. Well, if nothing helps at all, and you want to get the coils out as soon as possible, use the chemicals according to the instructions, but again, plant the noble snails so that they do not suffer.

Rotifers

Be careful this vide HAS SOUND!

Rotifer facts: little known wheel animals | Animal Fact Files
Plankton sizes from 0.03 mm to 0.2 mm. The fact is that the rotary apparatus in rotifers constantly rotates, and is used not only as a mouth but also as an engine. Harmless, filter water, and are, along with artemia, ideal food for the fry of any fish from the first days of life.

Rat tail maggots

Rat tail maggots

As you can see, these organisms actually look like a rat because of their “tail”, in reality, the tail is more correctly called not the tail, but the proboscis. Eritalis captures atmospheric air with this proboscis. The rat is the larva of a female fly, eaten by fish so willingly that it is unlikely to survive to the stage of an adult fly.

Livoneca (Livoneca amurensis)

Livoneca (Livoneca amurensis)

A real aquarium vampire. Small crustacean parasitic in fish. Most often sucked near the gills or in the mouth. You can bring into the aquarium with fish brought from the natural range, that is, with wild ones. Single individuals are removed manually with tweezers. If the damage to the fish is multiple, use special medications. You can use just potassium permanganate, but this is dangerous, a small error with the concentration of the solution promises big problems, especially in sensitive fish, for example, Characidae. Fortunately, the Livoneca does not breed in the aquarium, since it must pass through the larval stage before adulthood, but at that time it will be almost completely eaten.

Black soldier fly larvae (Hermetia Illucens)

Black soldier fly larvae (Hermetia Illucens)

Soldier fly larvae is a fly, its larva resembles a worm 0.3 cm in size, its color is different, from white to light shades of brown. Both larvae and pupae are coated with a kind of calcium carbonate armor. It is safe for fish, feeds on the remains of food. Therefore, like a mantra, we repeat: it is not worth overfeeding aquarium fish.

Dragonfly larvae

green dragonfly larvae (larva de libelula verde)
Dragonfly larvae can imperceptibly enter an aquarium with bunches of aquatic plants. But if you saw this monster in your aquarium – immediately remove it from there, the net and sleight of hand to help you. The dragonfly larva is a long-lived (a year or two) and dangerous predator, fish fry in such a neighborhood are in mortal danger, and small fish too.

Larvae of a Whirligig beetle (Dytiscus)

Group 21: Water Beetles (adults and larvae) Gyrinidae sp. [Whirligig larva]
And again an alarming trill plays in my head. The larva of a Whirligig beetle Dytiscus brought from a reservoir is also a dangerous predator hunting for fish. Catch and immediately eliminate.

Hydrophilidae larvae

HYDROPHILIDAE LARVAE
A thick, clumsy black worm. Hunts various snails. It is quite easy to notice, since from time to time the larva is forced to rise to the surface in order to replenish the supply of air, and since it is extremely difficult for it to swim in the water column, it moves along the stems of plants.

Bryozoa

Bryozoa

These creatures are very similar to tentacles, they grow in size from 1 to 3 mm in a colony, which is why they are very similar to corals in the Avatar movie:)

Do I have to deal with bryozoans? In response to this question, the opinions of aquarists differ, on the one hand, they eat ciliates and bacteria, this is useful, which means bryozoans are helpers and there is no need to fight. But we must make sure that they do not accidentally populate the filter sponges and begin to feed on nitrifying bacteria. If there are too many bryozoans, more frequent water changes, and aquarium cleaning will help.

Roundworms ( nematodes  ) and Stylaria

Roundworms ( nematodes  )

Thin white worms do not present any particular danger, usually, the fish themselves cope with the nematodes by having a hearty breakfast, lunch, and dinner.

Ostracods (Cypridopsis vidua)

Be careful this vide HAS SOUND!

Seed Shrimp - Ostracods: Friend or Foe in Freshwater Fish and Shrimp Aquariums?
Crustaceans less than 1 mm in size. They eat the decaying remains of plants and food, fish will fight for them. According to the experience of many aquarists, sharp outbreaks of ostracods occur in densely planted herbal aquariums, where there are a lot of soft plant debris and few fish.

Slime mold

Slime mold

Strictly speaking, this is mold. Scientists believe that this mushroom is intelligent, it knows how to move, and is constantly looking for food, as soon as part of the mycelium stumbles on something edible – it immediately begins to secrete digestive enzymes. You can cleanse the organism from surfaces mechanically or use antifungal drugs.

Aquatic flatworm (Dendrocoellum lacteum)

Group 1: Flatworms (Dendrocoelum lacteum)
Flatworms, covered with fine hairs, have venom glands that prevent most fish from feeding on them. They can get into the aquarium in many ways: water, new plants, new soil, poorly processed live food, etc. They are capable of reaching huge sizes of several centimeters. It is able to recover to its full size from a piece that does not exceed 0.5% of the original body. They eat everything that gets into their mouths, from caviar of snails to shrimp and small fish. To combat planarians (flatworms), special traps are produced, where a certain delicacy is applied, beef heart, for example. Since the planaria lead a nocturnal lifestyle, in the evening we “charge” the trap, and in the morning we get the catch, we methodically repeat these actions until we survive the enemy from our territory. If such a gentle method does not help, you will have to resort to chemical attack with specially designed drugs. Albendazole does an excellent job with planaria.

Poduridae

Poduridae

Small arthropods up to 2 mm in nature live on the surface of ponds, in an aquarium they often live under a cover, where the optimal level of humidity is maintained by water vapor, and food sometimes falls on the ribs of the aquarium. They are not dangerous. The way to fight is more accurate feeding.

Ranatra

Ranatra

Refers to stick insects, water bugs, rather large, 3 – 3.5 cm, 1.5 cm of which is the respiratory tube. It feeds on aquatic insects, so in theory, it can be dangerous for small fish.

Snail leech

snailleech leech - alboglossiphonia weberi eating a snail
It is similar to planaria but differs in smaller size and brown or brown color, the leech is brought in most often with soil. You can use salt to fight, but with great care, as salt can harm the snails themselves. Recipes for making baths vary, for example, there is such a place to place snails in 1 liter of water, after dissolving 2.5 teaspoons of salt in it. The bath lasts 10 minutes.