How To Get Rid of Fish Lice on Goldfish

You have a pet goldfish and are struggling with how to treat the fish lice on goldfish. Fish lice can cause your fish to scratch itself, and they look gross.

Fish lice are unpleasant parasites that can make your goldfish sick. Read the guide on fish lice treatment to get rid of those nasty parasites.

Fish Lice on Goldfish


Causes of Fish Lice on Goldfish

Branchiouran crustaceans belonging to the fish lice family that are infested and cause problems in fish are called fish lice (Argulus spp). Approximately 100 different species of Argulus are spread out all over the world.

Three of the many studied species of Argulus foliaceus, Argulus japonicus, and Argulus coregoni are found in freshwater systems.

Argulus japonicus is native to Asia, particularly in an environment where common goldfish (Carassius auratus).

What Do Goldfish Lice Look Like

Fice Lice

Argulus is commonly recognized by its dorso-ventrally flattened body form that’s covered by a chitinous carapace. Cephalothorax, thorax, and abdomen are 3 body parts of its body.

The population of Argulus foliaceus causes the itchy skin attributed to the flicking of the fins.

The mucus production on the skin surface and the appearance of small hemorrhages might lead to spread among the skin.

When Do Fish Lice Prevalent in Goldfish

Fish lice infestations tend to peak in summer and fall. The louse can be tied to the skin surface.

Argulus is also able to act as a mechanical vector or intermediate host for a number of fish diseases.

The parasite can transmit and carry a writing-like finding in carp the disease variously known as spring viremia, viral common carp, and goldfish among hosts.

Signs & Symptoms of Fish Lice on Goldfish

Spot or puncture hemorrhages, anemia, fin, and scale loss.

-The skin and fins have a vast array of reddish spots and hemorrhagic areas.

-Lethargy, abnormal swimming, and poor growth.

-Small dark spots on the skin, normally behind the fins and right behind the chin.

-Abundant mucus and hemorrhages were observed on the skin and surrounding areas, the causes of which were loss of cells and tissues.

-Goldfish may rub against surfaces in an attempt to relieve pain or to get rid of the parasites.

-Secondary infections caused by the parasites sometimes become necrotic and ulcerated, resulting in more pathologies.

Life Cycle of Fish Lice

These organisms have direct life cycles (requiring one host), and Argulus and A. japonicus are dioecious, which means the sexes occur separately.

Only the female Argulus lice are successfully ovulating. The males possess large testes, which can be seen from within when a specimen of these bugs is alive.

Mating typically occurs on the epithelium of the host fish after a female louse detaches from it. Eggs are typically 1 to 9 in length and width and are covered with gelatinous excreta that are deposited on hard surfaces in 1 to 6 rows.

They hatch in 10 days at 35°C but require another 61 days to hatch at 15°C. Newly hatched or notils survive 1 to 2 days by obtaining nutrition from their yolk sacs and later get it from epithelial cells and mucus of the hosts.

Argulus lice propel themselves through the water efficiently when they seek another host; propulsion comes from four pairs of legs located posteriorly on their ventral surface.

On the ventral surface of the louse are short hooks and antennae, each of which possesses claws and functions as a hook for attachment to the host.

Young Argulus lice use claws as an attachment to the host, whereas adults use modified suckers to anchor themselves. The majority of the Argulus life cycle takes place on the body of the host fish in 30 to 100 d.

In particular, Argulus japonicus lays eggs from spring to early winter, which may take as long as six weeks to fully hatch.

The length of time it takes an Argulus egg to go through its life cycle is about two months, making the process worthwhile of eliminating bacteria by disinfecting the tanks or allowing them to dry for a while.

Manual removal, as we have been doing at our location, is also efficient.

Diagnosis of Fish Lice on Goldfish

Because of their size, mature stages of Argulus can be diagnosed by the naked eye and can be seen swimming around in the water or moving the host.

In addition, you can catch the parasite on a moist mount colloquially known as a lesion.

Differentiation between A. japonicus and other, similar animals, especially A. foliaceus and A. coregoni, is based on their physical appearance.

How To Treat Fish Lice on Goldfish

An initial course of organophosphates, in most cases 2-3 doses once per week, is typically required for treating the early larvae and juveniles.

The owner was advised to disinfect the aquariums and equipment to cleanse thoroughly eggs, and treatment of fish with trichlorfon (0.25 mg per liter under conditions less than 27 degrees Celsius, or 0.50 mg l from 27 to 36 degrees Celsius).

-The bath was repeated twice a week and was found going well. To eradicate Argulus, treatments such as trichlorfon (0.25 ppm for several hours) and emamectin benzoate can be used.

-Oral enamectin is also an effective treatment. Other treatments of Argulus infestations include the use of common chemicals such as salt (NaCl), formaldehyde, potassium permanganate (2-5 mg per liter of the bath), and formalin.

-It is possible to remove Argulus using tweezers or forceps throughout the fish, but it can be tricky to locate and remove all Argulus.

How To Prevent Goldfish Lice

The key to preventing the spread of parasites is avoidance and quarantine. Goldfish should be carefully inspected for the occurrence of the parasite before buying.

-In addition, plants and other organic matter eggs can be laid on to bring the parasite into a pond or aquarium.

Source water should be evaluated to ensure it is not a pathway for the introduction of Argulid eggs.

-Screening and quarantining incoming fish are necessary at home to avoid Argulus infestation. Incoming wild-caught or pond-raised fish should be screened and quarantined to prevent from the introduction of Argulus eggs.

-After each use, the nets are disinfected in a solution of 2 ounces of 6% bleach in half a gallon of tap water.

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