Leeches in Freshwater Fish Treatment

Leech on the back of a fish

In most captive-bred freshwater aquarium fish, leeches are a rare parasite. If you're bringing in a wild animal, though, keep an eye out for leeches and other parasites. A veterinarian's accurate identification is necessary for optimal therapy.

What are leeches?

Leeches are a sort of worm that clings to an animal's skin and feeds on the blood of its host. They are earthworm cousins and belong to the Hirudinea subgroup of the phylum Annelida. Although most leeches dwell in freshwater, a few species may be found in saltwater environments.

Symptoms of Leeches in Freshwater Fish

  • Leeches hanging off fish's body, in oral cavity or gill cavity
  • Pale gills
  • Lethargy
  • Increased respiration
  • Negative buoyancy

Small leeches are difficult to see until they develop in size. Any elevated, black lines on your fish might be a natural color, traumatic wounds, or a little leech. A physical examination by your veterinarian will decide if the color deficiency is normal or whether it is caused by a harmful infection.

Many clinical symptoms of blood loss include pale gills, tiredness, increased breathing, and lingering near oxygen sources like filter outputs or air stones. can be induced by a variety of factors, the most prevalent of which are dietary inadequacies.

Buoyancy issues are fairly frequent as a result of a variety of stressors. When low-energy fish can't get enough nutrition or oxygen, they develop negative buoyancy diseases. Blood loss is the major cause of sluggish, negatively buoyant fish in leech infestations, simply because they lack the energy to swim.

Causes of Leeches

Leeches will infiltrate the systems of infected people who have not been appropriately quarantined. They can conceal within a fish's opercular or oral cavity, making them difficult to detect at first. In order to reproduce, two leeches must be present. Despite being hermaphroditic, they begin life as men and develop ovaries later in life. Leeches, unlike other worms, can only reproduce sexually and cannot regrow parts of their bodies.


If you notice a leech on your fish, the best therapy is to physically remove it as soon as possible. If you're confident handling your fish, go gently and use two nets to catch it fast and efficiently. Keep them in the net and remove the leech with a pair of tweezers. It is vital that the leech be removed from the system or else it will attach to another fish. Be aware that squeezing the leech may result in a big amount of blood gushing out!

Call your local aquatic veterinarian if you are uncomfortable or hesitant about touching your fish. They'll sedate and capture your fish securely for simple leech removal. Your veterinarian will be able to inspect all orifices of your fish during a sedated physical exam to ensure there are no new leeches on your fish, particularly in the mouth cavity or gills.

How to Prevent Leeches

Leeches on captive-bred fish are quite uncommon. Leeches are most commonly seen in wild-caught fish. To safeguard wild supplies, try to avoid taking any fish from the wild. If you catch fish in your local stream or lake, please return them to their natural habitat rather than taking them home.

If you must buy wild-caught fish, quarantine all new arrivals in a separate, isolated system for 4-6 weeks. Separate equipment should be used for each system, and water from one system should not be allowed to splash into another. Keep a watchful check on your new recruits, and if anything seems off, a prompt diagnosis and efficient treatment are your best hope for their survival. It's a good idea to keep the contact information for your local aquatic veterinarian on hand in case you have any queries or want immediate assistance.

Are Leeches Dangerous to Humans or other Pets?

Leeches are parasitic parasites that may easily attach to humans or other animals. Crush the head of a leech with the tweezers you used to remove it from your fish. Keep in mind that this might result in a flow of blood. Humans and other pets are not poisoned by fish blood, but contact locations should be thoroughly cleaned with soap and water. If you don't kill the leech, it can attach itself to you, another person, or one of your pets.