Freshwater Tropical
Hexamita (Hole-in-the-Head)
Intestinal flagellate parasite causing pitted lesions on the head and lateral line, especially in cichlids and discus. Often…
Moderate
Parasite
Marine / Saltwater
Marine Ich (Cryptocaryon irritans)
Saltwater white-spot disease. A 2006 resistant strain renders traditional copper and formalin treatments ineffective — quinine sulfate is…
Severe
Freshwater Tropical
Freshwater Ich (White Spot Disease)
The most common freshwater fish disease. Tiny white spots resembling grains of salt cover the body and fins.
Moderate
Freshwater Tropical
Velvet (Oodinium)
Dinoflagellate parasite producing a fine, gold-dust coating across the body. More lethal than ich; gill infection causes rapid…
Severe
Freshwater Tropical
Costia (Ichthyobodo)
Parasite (flagellated protozoan) disease of aquarium fish. Key signs: blue-grey film of mucus over skin ('slime disease'), peeling…
Moderate
Freshwater Tropical
Trichodina Infestation
Parasite (ciliate protozoan) disease of aquarium fish. Key signs: excessive mucus (slime coat), pale or 'milky' patches on…
Moderate
Freshwater Tropical
Gill and Skin Flukes (Dactylogyrus & Gyrodactylus)
Parasite (monogenean flatworm) disease of aquarium fish. Key signs: increased mucus on gills/skin, flashing, gasping at surface, frayed…
Moderate
Freshwater Tropical
Fish Lice (Argulus)
Parasite (branchiuran crustacean) disease of aquarium fish. Key signs: flat, round, 5–10 mm semi-transparent lice visible attached to…
Moderate
Goldfish
Anchor Worm (Lernaea)
Parasite (copepod crustacean) disease of aquarium fish. Key signs: greenish-white thread-like worms protruding from skin (the female parasite…
Moderate
Freshwater Tropical
Hole-in-the-Head Disease (Hexamita)
Parasite (flagellated protozoan) disease of aquarium fish. Key signs: pinhole-sized pits on head that enlarge into cavities; lesions…
Moderate