Bothriocephalus sp.

Today we will show you the Asian – Bothriocephalus sp. – tapeworm. Bothriocephalus sp. is a genus of parasitic flatworms. These parasites are known for causing significant damage to fish populations. This ‘white filamentous feces in fish’ can have several causes! When you notice that your fish has white feces, you should take a closer look into determining what has caused it. This article will provide an in-depth look at the biology and lifecycle of Bothriocephalus sp., its effects on fish health and the treatments you can use to get rid of them.

What is Bothriocephalus?

Bothriocephalus sp. is an Asian tapeworm which is one of the most widely spread tapeworm species in freshwater fish. Originating from the Asian gras carp, Botriocephalus achneilognathi can infect fish that belong to many different groups: for example, Cichlidae, such as the orange parrot fish and Discus fish, but also Cyprinodontidae, Siluridae, Poeciliidae, Cyprinidae, Acipenseridae and Atherinidae species. This includes fish like carp, catfish, guppies, platies and swordtails.

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Adult Bothriocephalus can vary in length from 1 to 100 cm. They are able to adapt their own size to the size of their host, which is a rare ability. For example, a fully mature worm of only 1.5 cm in length was found in this swordfish. In another example we have found worms of up to 25 cm in length in adult discus fish.

The parasite feeds itself by absorbing nutrients through the surface of its body. Their presence in the intestines of the fish cause severe problems, like blockages and disorders of the digestive system, which lead to a lack of nutrients and often to emaciation. On the other hand, if many worms are present in the intestines, you may observe a considerably enlarged belly as if the fish had eaten well. But if the belly does not disappear after a few hours, you know there could be something wrong.

The worm’s body is divided into segments, each bearing hundreds or even thousands of eggs. To get the eggs into the external environment, the worm sheds several segments, which leave the intestine encapsulated inside the feces of the fish. This is where it becomes visible there is a problem in your aquarium. Aquarists start finding strange segmented white “feces” of varying sizes at the bottom of the aquarium. These worms can also be protruding from the anus. And sometimes, although rarely, even from the mouth of the fish! This can be quite shocking to see!


When combating tapeworms in fish, the peculiarities of the parasite’s life cycle and the water temperature must be taken into account. The eggs of the parasite get into the surrounding habitat through the fecal matter of fish. At a water temperature of 28 to 30 degrees Celsius you will see free-floating larvae hatch within 1 to 5 days. The colder the water, the longer the larvae take to hatch. For the next stage of development, it is necessary that the larvae are eaten by Copepoda, for example, Cyclops. The tapeworm larva develop in the body of the cyclops for another 6 to 10 days. When fish eat these cyclops, the larvae of the parasite can attach themselves to the intestinal wall of the fish and begin to develop into adult worms, producing hundreds, sometimes even thousands of eggs.

It’s important to understand that when fighting Bothriocephalus in aquariums, it’s not only necessary to eliminate the parasite itself, for example by using eSHa gdex, but also to exterminate the larvae carrying intermediate crustacean hosts, to break the development cycle. To do so, we recommend using eSHa alx.

Treatment of our fish

In our case, on the bottom of the aquarium with discus fish, we found white “feces”, which were the parts of a tapeworm. It is easy to determine if these are indeed worm parts lying at the bottom of the aquarium, just arm yourself with a magnifying glass and carefully look at them. When you observe the segmented structure, any doubts you may have had will disappear: it is a indeed a tapeworm and not feces. But don’t think that your fish got rid of the worms, because the problem is that the worms are still inside the fish and only their segments, stuffed with eggs, are on the bottom of the aquarium. It is necessary to treat the fish and make sure that the worms, which have club-shaped heads, come out of the fish. eSHa gdex comes to the rescue!

As a result of our eSHa gdex treatment, 13 worms with different lengths, came out of this discus! Because of this infection, the fish was also experiencing a lot of stress, swimming frantically and bumping into the walls when people approached the aquarium. When your fish show this type of behavior it is worth looking at what caused it. We have treated this fish and at this time this discus is so relaxed, that it even takes food directly from our hands!

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