Aquarium Fish Disease Guide Find Causes and Care Articles by Symptom

A fish's appearance and behavior offer clues, but they can't confirm a disease on their own. This index organizes the series by symptom to help you check water quality and recent changes first, then learn about possible causes, how to confirm them and key points of care.^[1][2]

◑Deal with breathing problems and equipment failures first

If several fish suddenly gasp at the surface, breathe rapidly or lose balance, first check aeration, filtration and the water source, and measure water temperature, pH, ammonia and nitrite. Contact an aquarium fish veterinarian at the same time as needed; don't delay dealing with an obvious acute problem in order to read through the articles one by one.^[1][2]

◑Find articles by the symptoms you see

One symptom may correspond to several articles, because environmental problems and infections can occur at the same time. The index is meant to narrow down what to check, not to choose a medication directly from a symptom.

◑What information to prepare before submitting samples

Gather the species, number of fish kept, when illness first appeared, death records, water quality readings, changes in feeding and water changes, and a complete medication record. Prepare the fish and the original tank water sample separately, and ask the diagnostic lab about its submission and storage requirements first.^[3]

◑The complete series

• What to Do When Your Fish Is Sick – Reading Aquarium Fish Symptoms and What to Do First→
• Ammonia and Nitrite Poisoning – Fish Gasping at the Surface and How to Read Water Test Kits→
• How to Quarantine New Fish – Isolating for at Least 30 Days and Acclimating Fish to the Tank→
• White Spot Disease (Ich) in Freshwater Fish – The Ichthyophthirius Life Cycle and Why It Keeps Coming Back→
• Velvet Disease in Freshwater Fish – Gold-Dust Symptoms and How It Differs from Ich→
• Columnaris Disease Symptoms – Recognizing Rotting Gills and Fins and Cottony Growth on the Mouth→
• Is White Fuzz on Your Fish Water Mold? – Wound Infections and Why Fish Eggs Grow Fuzz→
• Causes of Dropsy and Raised Scales in Fish – How to Assess a Swollen Belly and Pinecone Scales→
• Parasites Visible on Your Fish – Identifying Anchor Worms and Fish Lice and Understanding Their Life Cycles→
• What Causes Hole-in-the-Head Disease – The Evidence on Activated Carbon, Flagellates and Nutrition→
• Goldfish Floating Upside Down or Head-Down – Causes of Buoyancy Disorders and When to See a Vet→
• Monogenean Parasites of the Gills and Skin – Why Fish Breathe Fast and Flash→
• White Stringy Poop and Ongoing Weight Loss in Fish – Sorting Out Internal Parasites and Feeding Problems→
• Flashing, Clamped Fins and Excess Slime in Fish – Telling Skin Parasites from Water Quality Irritation→
• Red Patches, Bleeding and Ulcers on Fish – Telling Injury from Bacterial Infection→
• Fish Gasping or Dying After a Water Change – Tracking Down Chlorine, Chloramine and Water Quality Changes→
• Popeye and Cloudy Eyes in Fish – Sorting Out Eye Injuries, Water Quality and Infection→
• Wart-Like Growths on Fish – How Lymphocystis Disease Differs from Ich→
• What Is Fish TB – Mycobacterial Infection in Aquarium Fish and Everyday Precautions→