Parasitic Digestive Disorders in Fish

PetMD Editorial
By PetMD Editorial
Published: July 2, 2008
Parasitic Digestive Disorders in Fish

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.

Help us make PetMD better

Was this article helpful?

Get Instant Vet Help Via Chat or Video. Connect with a Vet. Chewy Health

Subscribe to PetMD's Newsletter

Get practical pet health tips, articles, and insights from our veterinary community delivered weekly to your inbox.