Black dots Disease on Fish and Its Cure

Diplopstomiasis, or fluke illness, is another name for black spot/dots disease. Flatworm larvae of the genus Neascus cause this disease in freshwater fish. It appears as small black patches on the fish’s skin, fins, and flesh. 

A fish-eating bird, a snail, and a fish are usually involved in the parasite’s life cycle. In the diseased bird’s intestine, the black spot larvae reach sexual maturity. Adult worms lay eggs in the droppings of birds. When the eggs reach water, they hatch into free-swimming organisms that subsequently enter snails to continue their development. Finally, they burrow into the skin of fish and develop a cyst after leaving the snails. The cyst is surrounded by black pigment, which lends the condition its name. 

It appears that when a bird eats an infected fish, the cycle begins all over again. 

Praziquantel and Formalin are the best chemical therapies for this condition. Osmotic shock (freshwater dips, hypersalinity) is another therapy option.

Why are there black dots in my fish?

Generally, black dots/spots disease in fish is commonly called as Diplopstomiasis or fluke illness.

It appears as small black patches on the fish’s skin, fins, and flesh. The dark dots on the fish’s skin that you can see and feel if you rub your fingers over them are tiny cysts. They’ll be strewn throughout the flesh of a badly afflicted fish. And, if you mistakenly eat one, you’ll notice that it’s crunchy, like a speck of sand or a piece of peppercorn. 

Fish skin, fins, and flesh are infested with parasitic flatworms that appear as tiny black dots. This problem can’t be solved because there isn’t a way to regulate it but can be cured. The biggest issue with black spots is the unattractive appearance they might have. Most black spots can be removed by scrubbing sick fish.

Fish flukes are parasitic parasites that infect fish’s skin and gills. They attach themselves to the fish with a set of “hooks” and begin sucking blood and bodily fluids, weakening it. Colour loss, trouble breathing, excessive mucus secretion, listlessness, clamped or frayed fins, flaring gills, and little blood spots on the fins and body are all symptoms. Fluke outbreaks, like most fish diseases, are mainly triggered by stress induced by poor water quality, incorrect food, overcrowding, or other fish hostility.

Does Black spot disease kill fish?

Digenean trematodes (flukes) in the families Diplostomatidae and Heterophyidae cause black spots. Trematodes’ cercarial forms penetrate a fish’s skin, where they encyst and mature into metacercariae. In response to the alien organism, the fish covers the cyst with black-colored melanin. The black specks can frequently be seen with the naked eye. These worms can be found in both freshwater and saltwater fish. 

So in general black spot disease is not harmful so far to a fish but if not cured it can affect that fish as well as other fish living in that environment. 

They use hooks to attach themselves to the host (fish) and begin sucking blood and body fluids, therefore its body became weak. Symptoms include color loss, difficulties in breathing, increased mucus secretion, listlessness, clamped or frayed fins, flared gills, and small blood spots on the fins and body. 

However, because it causes annoyance and stress, it is advisable to strive to get rid of them. The fish may go blind if the parasites concentrate on the eyes. 

Black Spot rarely kills fish (it’s not in their best interests for them to do so; they want the fish to live… and then be eaten!). So it is better to treat them in the right way.

How do you treat black spots in fish?

Exposure to water containing parasitized snails causes parasitism in fish. The snails’ actively swimming cercariae enter the fish’s epidermis, where they grow into metacercariae. Fish-eating birds and mammals are the definitive hosts, completing the life cycle by releasing eggs into the water with feces. Mira-cidia parasitizes the snail hosts once the eggs hatch into miracidia. 

Small, multifocal, slightly elevated black dots in the fish skin are used to make a presumptive diagnosis. Metacercariae in the cysts can be seen in wet mount preparations or histological sections for confirmation. Tissue sections reveal a thick, fibrinous capsule surrounding the encrusted metacercariae, with numerous melanocytes around the capsule’s periphery. Neascus is a larval genus that encompasses multiple genera and species of trematodes belonging to the Diplostomatidae family. More specific genus and species identification are based on the encysted metacercariae’s environment (marine or freshwater), tissue site of encystment, and other morphological traits.

  • A 10 to 30-minute immersion in 10 mg per liter potassium permanganate is the most effective treatment. Alternatively, treat the entire tank with 2 milligrams per liter, however, this procedure is untidy and causes the water to turn yellow. 
  • The best chemical treatments for this disease are praziquantel and formalin. Another treatment approach is osmotic shock (freshwater dips, hypersalinity).