Parasitic Digestive Disorders in Fish


PetMD Editorial

Updated Aug. 16, 2022

Digestive Disorders

Most digestive disorders in fishes are caused by parasite infections. However, not all parasites cause problems for fishes -- some live in a symbiotic relationship with the fishes.

Symptoms and Types

The symptoms can vary depending on the parasite causing the digestive disorders, but usually include weight loss, lethargy and loss of appetite. Young fishes are especially susceptible to digestive disorders and can die before any symptoms arise. Such parasites which cause these type digestive disorders include:


  • Protozoan parasites (e.g., Spiionucleus, Hexamit, and Cryptobia)
  • Worm parasites (e.g., tapeworms)

Protozoan parasites Spiionucleus and Hexamita infect the intestines of cichlids, bettas, gouramis, and other aquarium fishes. Apart from the symptoms listed above, fishes with these two parasites produce stool that is white and stringy. Cryptobia, another protozoan parasite, infects the stomach of African cichlids.


 Various living conditions which can cause digestive disorders in fishes include: 

  • Overcrowding of the aquarium, tank or fishpond
  • Shipping methods
  • Handling methods
  • Infected food
  • Stressful conditions


Anti-parasitic medicines can be used to clear out a tapeworm, Spiionucleus, and Hexamita infections. However, there is no treatment for a Cryptobia infection. Those fishes infected with this parasite eventually stop eating and then die.

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