Causative agent: Pleistophora hyphessobryconis — microsporidian intracellular parasite
Neon Tetra Disease (NTD) is a devastating and incurable illness caused by the microsporidian parasite Pleistophora hyphessobryconis, and it represents one of the greatest threats to the neon and cardinal tetras that are so popular in Australian community tanks. The disease is insidious in its early stages — a slight fading of colour near the dorsal fin may be the only sign before the infection progresses to whitish cysts under the skin, spinal curvature, and complete physical deterioration. Because the parasite lives inside the fish's muscle cells, no medication can reach it effectively, and there is currently no known cure. The disease spreads when healthy fish consume the flesh of infected or dead fish — a behaviour that occurs naturally in a community tank. The only responsible course of action is early identification, immediate removal, and humane euthanasia of affected fish. Quarantining all new fish purchases for at least two weeks before adding them to a tetra community is the most effective preventative measure.
Symptoms
- •Colour fading starting near dorsal fin
- •pale white patches under skin
- •bent spine or scoliosis
- •abdominal bloating
- •difficulty swimming
- •visible cysts under skin
- •progressive wasting
Treatment
- •No effective cure — infected fish should be humanely euthanised to prevent spread
- •improve nutrition for remaining fish
- •strict quarantine
Australian Medications
- •No specific treatment available in Australia or elsewhere
Commonly Affected Fish
- •Neon tetras, cardinal tetras
- •also affects some danios, rasboras, and other small tetras
Important Notes
No cure exists. Euthanise affected fish immediately to prevent spread. Do not allow fish to eat infected or dead tank mates.