Fish Diseases

Ammonia Poisoning in Fish — Recognizing and Reversing It Before It's Fatal

Anchor Worms (Lernaea) — The Parasite You Can See and Physically Remove

Bacterial Infections in Fish — Recognizing the Common Patterns

Brooklynella (Clownfish Disease) — A Fast, Dangerous Parasite Disproportionately Affecting Clownfish

Camallanus Worms (Red Worm Disease) — The Parasite Visible at the Vent

Columnaris (Cotton Wool Disease) — A Fast-Moving Bacterial Infection

Costia Infection (Ichthyobodo) — A Fast-Killing Parasite of Stressed, Crowded Fish

Dropsy in Fish — What It Really Is and Why the Prognosis Is Often Poor

Egg Binding in Female Fish — When Eggs Can't Be Released

Epistylis Infection — The Fuzzy White Patches That Aren't Fungus

Fin Rot — Complete Guide to Causes, Stages, and Treatment

Fish Lice (Argulus) — A Large, Mobile Crustacean Parasite

Fish Tuberculosis (Mycobacteriosis) — A Chronic, Difficult-to-Treat Bacterial Disease

Fungal Infections in Fish (Saprolegnia) — Identification and Treatment

Furunculosis — Bacterial Boils and Ulcers in Fish

Gill Disease and Hyperplasia — Chronic Gill Damage in Aquarium Fish

Gill Flukes (Dactylogyrus) — The Hidden Cause of Chronic Gasping

Head and Lateral Line Erosion (HLLE) — A Chronic Condition With a Debated Cause

Hole-in-the-Head Disease (HITH) — Causes and Treatment

Ich (White Spot Disease) — Complete Guide to Identification and Treatment

Internal Parasites and Worms in Fish — Recognizing and Treating a Common but Under-Diagnosed Issue

Lymphocystis Virus — Cauliflower-Like Growths That Usually Resolve on Their Own

Marine Ich (Cryptocaryon irritans) — The Saltwater Equivalent With a Tougher Life Cycle

Neon Tetra Disease — The Incurable Disease That Isn't Always What You Think

New Tank Syndrome — Why Fish Die in the First Few Weeks of a New Aquarium

Nitrite Poisoning (Brown Blood Disease) — Causes and Treatment

Popeye (Exophthalmia) in Fish — Causes and Treatment

Saprolegnia Fungal Infection — The Classic Cotton-Wool Growth

Septicemia (Red Streaks and Hemorrhagic Disease) — A Systemic Bacterial Emergency

Skin Flukes (Gyrodactylus) — The Fast-Reproducing Cousin of Gill Flukes

Swim Bladder Disease — Why Fish Float, Sink, or Swim Sideways

Swim Bladder Disorder in Fancy Goldfish — A Body-Shape Problem More Than a Disease

Uronema marinum Infection — An Opportunistic Marine Parasite That Strikes When Fish Are Already Weakened

Velvet Disease (Oodinium) — Identification and Treatment Guide

Wasting Disease (Chronic Weight Loss) — When a Fish Loses Condition Despite Eating