Water Mites Profile: Water Mites in Shrimp and Fish Tank

Water Mites Profile Water Louse in Shrimp and Fish Tank

Water mites from the family Hydrachnidae are natural micro-predators and parasites. Due to their small size, they can easily find their way into almost any aquarium.

However, aquarists should not panic, if they see them in the tank as Water mites are practically harmless to fish, shrimp, frogs, and other aquatic inhabitants.

So, if you found Water mites in your tank, or simply want to know more about them, in this article, I will provide a comprehensive overview including their habitat, lifecycle, and more.

Distribution of Water Mites

Water mites inhabit freshwater ecosystems all around the world. They can be found in diverse geographical regions, from temperate to tropical climates.

Habitat of Water Mites

Different species of Water mites can be found in various aquatic environments. There are two families of water mites, which comprise more than 4,000 species:

  1. Hydrachnidae: Freshwater water mites.
  2. Halacaridae: Inhabit marine water.

Freshwater water mites inhabit ponds, lakes, rivers, streams, and even temporary water bodies.

Description of Water Mites

What is This Thing in My Tank - Water mitesSometimes Water mites are mistakenly classified as insects, but in reality, all their representatives are arachnids.

Size. Water mites are usually very small, ranging from 0.08-0.12 inches (2 – 3 mm) in size.
Note: Hydrachna geographica is the largest known species, reaching lengths of up to 0.3 inches (8 mm).

Body shape.  They have rounded or elongated bodies.

Body segmentation. The body is shortened, and unsegmented, with the fusion of the cephalothorax and abdomen.

Coloration. Their coloration can vary but, in most cases, they are brightly colored (red tones predominating). Nonetheless, besides red, other colors include blue-green, orange, yellow, brown, etc.

Eyes and Antennae: Their paired eyes are enclosed in chitinous capsules. They also have two long antennae-like setae between the eyes.

Legs: Water mites have 4 pairs of swimming or crawling legs, each with 6 segments and 2 claws at the end.

Interesting fact: Water mites breathe through their entire body surface, absorbing dissolved oxygen from the water, and can survive even in extremely low.

Live Cycle of Water Mites

Water Mites Profile Water Louse in Shrimp and Fish Tank 2The specific details of the life cycle can vary among different species of water mites. Some species may have additional nymphal stages or exhibit different behaviors during each stage of development.

Nonetheless, generally, the life cycle of water mites typically involves 5 stages:

  1. Egg: The life cycle begins with the laying of eggs by adult water mites. The eggs are often attached to underwater surfaces such as rocks, driftwood, vegetation, etc.
  2. Larva: Once the eggs hatch, larvae emerge. Larvae are usually six-legged and actively seek out hosts for parasitism.
    Note: In addition to feeding, parasitism has a dispersal significance; the larvae are carried by insects to new water bodies and then released into the water.
  3. Protonymph: After the larval stage, water mites enter the protonymph stage. During this stage, they have eight legs. Protonymphs may continue to parasitize hosts.
  4. Tritonymph: The mite undergoes further development.
    Note: Depending on the species and temperature, the duration of all larval stages ranges from a few weeks to several months,
  5. Adult: The final stage is the adult phase, where water mites reach sexual maturity. Adults become micropredators.

Lifespan of Water Mites

The lifespan of water mites can vary, but generally, adult water mites can live for 1 – 1.5 years.

Typical Behavior of Water Mites

Water mites exhibit swimming and crawling as their primary modes of movement.

Most species display excellent swimming abilities.

They swiftly navigate in various directions, manipulating their legs covered with tufts or rows of long bristles, resembling miniature oars.

Some species can crawl on aquatic plants and predominantly lead a benthic lifestyle, adhering to the bottom.

Diet of Water Mites

Adult stages of water mites exhibit predatory behavior as free-living predators.

They usually prey on various small animals, primarily targeting cyclops and daphnia, insect larvae, and other water mites with soft exoskeletons.

Water mites catch their food using their palps and front legs. After that, they use the clawed part in their mouth to pierce their prey and suck out the insides of their prey.

Generally, after feeding, only the chitinous exoskeleton remains, as even the muscles, under the influence of digestive secretions, are sucked out.

Water Mites Profile Water Louse in Shrimp and Fish Tank feeding on water scorpionMost water mite larvae (and sometimes adult species) parasitize other aquatic invertebrates, such as mollusks, Waterbugs (diving beetles)., water scorpions, dragonflies, and other invertebrates.

However, due to their small size, larvae generally do not cause significant harm to their hosts. The pests can live on their hosts during the whole cycle of the transformation, but it’s not always necessary for them. They can also change hosts multiple times.

Are Water Mites Harmful to Fish and Shrimp?

Water mites are considered harmless to fish, shrimp, and other animals in aquariums. They may parasite but generally, are not known to pose a threat to large organisms.

The bright coloration of water mites is often considered a warning signal. Indeed, many predators tend to avoid these mites.

In aquariums, it’s not uncommon to notice fish doing a little taste test with water mites and then spitting it out, indicating that the mite is not suitable as food.

However, when fish get a bit hungry and food options are limited, they may start consuming water mites anyway.

Are Water Mites Plants Safe?

Yes, water mites are absolutely safe for aquatic plants in an aquarium. They are predators and do not feed on plants.

How Do Water Mites Get in Our Aquariums?

Water mites are great hitchhikers. They or their eggs usually sit on aquatic plants, decorations, or even on other aquatic animals introduced to the aquarium.

Additionally, their larvae could be present in water from natural sources, such as tap water or water used to clean aquarium equipment.

Therefore, the usual recommendation will be to carefully inspect and quarantine any new additions to the aquarium and to regularly clean and maintain the tank to minimize the risk of introducing unwanted organisms.

How to Get Rid of Water Mites in the Aquarium?

Despite their small size, the red or orange color of their bodies makes them easily visible even to the naked eye. Therefore, it is quite easy to remove them manually. The only problem is that their larvae and eggs may still be there.

So, if you have decided to completely remove Water mites, you may have to completely restart the aquarium, as these arachnids are quite resilient.

  1. Move all aquarium inhabitants to a separate (quarantine) container. Ideally, it should be bare-bottom, without plants and minimum decorations. Carefully inspect your animals to identify any potential parasitic mites.
  2. Remove substrate. It can be difficult (I would say impossible) to find all mite eggs or larvae. Thus, dispose of the substrate without hesitation.
  3. Vacuum. Vacuum all corners and joints of the aquarium to remove any remaining substrate particles.
  4. Clean. Thoroughly clean the aquarium using a sponge. Rinse the aquarium thoroughly. Cleaning the tank will help remove any remaining mite particles.
  5. Sterilize decorations. Use bleach or boiling décor for around 5 minutes. It can significantly reduce the chances of retaining mite eggs on decorative elements.
  6. If you use sponge filtrations, you will have to replace it as well.

In Conclusion

Water mites are tiny arachnids that can inhabit shrimp and fish tanks. While they are generally harmless to aquatic life, their presence may indicate water quality issues.

For a healthy aquarium, quarantine and treat new décor (especially those sourced from nature) to avoid unwelcome guests.

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