Tapeworm

Tapeworms belong to the phylum Platyhelminthes (flat worms), class Cestoda. They are segmented flat worms. They have a head (usually the smallest part of the body), neck, and a number of segments. The head attaches to the fish's gut, but it has no mouth. The tapeworm absorbs nutrients through its skin directly from the fish's intestinal tract.

The small dots are brine shrimp. Tapeworms can easily be as long as the guppy host.

Each segment of the tapeworm has its own reproductive organs. New segments are continuously formed in the neck region, allowing the worm to continue to grow throughout its life. The segments are really egg packets and as they mature they are cast off. They are usually discharged from the body of the guppy in the feces. Tapeworms are extremely prolific.

Eggs are either distributed from a spore in the oldest segments, or the egg sack ruptures releasing all the eggs. Eggs hatch into a ciliated, free-swimming coracidium. Small copepods in the water ingest the coracidium.

The guppy in turn ingests the copepods.

There are different species of tapeworms, but the most common belong to the order psudophyllidea.

Many experts believe that tapeworms do no harm to the host. However a severe infection of larval tapeworm can be damaging to the fish, as they burrow into the guppy's tissues. Tapeworms can act as a host for other pathogens that are passed on to the guppy.

Tapeworms can live for several months, so they can accumulate in large numbers.

Symptoms and Behavioral Signs
The guppy may appear to be anemic. The tapeworm may rob the guppy of vitamin B12. However these are unreliable symptoms. Dissecting the guppy and examining it under a microscope may reveal an intestine jammed with intertwined tapeworms. Or the guppy may occasionally discharge an adult tapeworm. Large species of tapeworms can be identified with the naked eye, as they have a segmented body with a small round head.

Causative Condition
The guppy eats an intermediate host, such as a copepod, or eats feces that has eggs in it. Live tubifex worms are a noteworthy source of tapeworms.

Prevention and Treatment
New fish brought into the fish room should be dewormed and "defluked." The most effective treatment is praziquantel. The tank should be bleached afterwards.