Pleistophora hyphessobryconis

From Fish
Neon Tetra disease in the dorsal skeletal muscle

Neon Tetra disease is caused by the microsporidian parasite Pleistophora hyphessobryconis, which infects the skeletal musculature of a number of species of aquarium fish, including tetras, angelfish, rasporas, and barbs.

Infected fish may exhibit abnormal locomotion caused by muscle damage, and muscle tissue may appear marbled or necrotic at necropsy. The parasitic spores are readily visualized in wet mounts of infected tissue[1].

There is no treatment for the infection, although removal of moribund fish helps prevent transmission by eliminating cannibalism within the population.