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Tropical Fish Parasites, How to Identify

Drs. Foster & Smith Educational Staff
The Dangers of Overfeeding Fish 
Prevent a Warm Water Disaster 
Proper Fish Diet 
How to Identify Common Tropical Fish Parasites
The best prevention against parasites is to keep your fish healthy in a stress-free environment. Healthy fish rarely get sick even if exposed to infected fish unknowingly introduced into the aquarium. Proper aquarium setup and water parameters, routine maintenance, quality nutrition, and minimizing aggression among inhabitants are easy ways to improve fish health and reduce infection.

Common aquarium parasites
Despite our best efforts, most aquarists will need to deal with parasitic infection. The most common parasite in both fresh and saltwater aquariums is "Ich" or white spot disease. Other common fish parasites include anchor worms, black spot, costia, gill flukes, hexamita, fish lice, and velvet. All can pose a serious threat to the health of your fish. Because of their size, the presence of parasites is often diagnosed initially through abnormal fish behavior. Once the parasites are well established, physical damage can be observed on the infected fish.

Parasite Symptoms and Treatments
If you observe the behaviors described below, you may need to take corrective action*:

Disease Signs Recommended Treatment*
Anchor Worm
Anchor Worm: Photo courtesy TFH Publications
Whitish red worm-like threads approximately 1/4" in length, found anywhere on the body, fish may scratch on fixed objects Treat with an anti-parasitic medication; or treat aquarium with PimaFix to quickly clear external and internal parasites from tropical fish
Gill Flukes
Gill Flukes: Photo courtesy TFH Publications
Gills become covered with parasites, red and inflamed; fish may gasp for air at surface; listlessness Use General Cure™
Freshwater: Ich (Ichthyophthirius multifiliis)
Marine: Ich (Cryptocaryon irritans)
Ich: Photo courtesy TFH Publications
Labored breathing; dwelling near the surface, filters, or aeration devices; white spots; scratching on fixed objects Freshwater and Scaleless: Use Ich-Attack
Marine**: Use Cupramine as recommended. Use Garlic Xtreme as a preventive.
Fish Lice
Fish Lice: Photo courtesy TFH Publications
Visible parasite attached to fish, approximately 3/16" long and semi-transparent Use Cupramine
Freshwater: Velvet
Marine: Amyloodinium ocellatum
Velvet: Photo courtesy TFH Publications
Loss of normal color, scratching against fixed objects, labored breathing, golden "velvety" growth on skin Freshwater: Use Fritz Aquatics Mardel Herbal Treatments Parashield
Marine**: Use Probiotic Marine Formula or Cupramine

*Please note: Activated carbon will remove all medications from the aquarium. When using medication, activated carbon must be removed from the filtration unit.

- Perform a 25% water change before and after treatment period.

- In addition to treatment, be sure to determine and correct aquarium conditions that contributed to fish stress and susceptibility to disease.

**We recommend that treatment of marine fish be done in a separate quarantine aquarium.

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