Illness in Tropical Fish

When dealing with tropical fish illness and disease, it's always a good idea to have a good guidebook at your side. We recommend this book as a handy desktop reference.

Diagnosing illness in your tropical fish can be a difficult task, because many conditions may present some of the same symptoms.  If you cannot identify at least one sign that is solely the feature of a certain illness, then remove the fish to a hospital tank, and treat it with a medication suitable for the condition that it shows the most signs of.

Bacterial Diseases

A good example of this, are bacterial diseases.  At times, they may present a cottony coating on the body, which look like a fungus.  However, if the grey/white covering is observed along with red or orange spots, or red streaks on the body, that is evidence of bacterial infection. But that does not rule out the possibility that the two conditions have occurred together.  Bacterial infections are treated with tetracycline, penicillin and naladixic acid. In the very large species, it is possible to use injections. Otherwise, it requires either force-feeding, or putting the antibiotic in something like gelatinized food. Salt baths are also beneficial.

Fungal Diseases

Fungal diseases generally do not occur unless there has been damage to the epidermis, or external skin of the fish.  Depending on the severity of the problem, fish often manage to survive a minor occurrence with only standard good nutrition and a healthy environment. However treatment is easy, usually by removing the outer fungal growth with a moistened cotton swab, and treating the spot with a topical cream or ointment.

External Parasites

External parasites, or protozoal diseases, include conditions like Ichthyopthyrius, or common “Ich.  This particular condition has a cystic stage under the scales, which is untreatable at that point. It’s not until people notice their fish scraping against objects, that the problem is generally diagnosed.  Parasitic diseases have two sources: a diseased fish from outside the environment, or poor conditions inside the environment, e.g. overcrowding, and other stressors.  A single sick fish should be removed to a hospital tank for treatment, but if there are two or more affected, the whole tank should be treated as a precaution.  Once the parasites are killed off, follow up treatment should be carried out to avoid bacterial infection.

Internal Parasites

Internal parasites do not generally create emergency situations. If you suspect your fish of having something like a tapeworm, you can put it in a hospital tank to obtain a fecal sample for examination.

Remember: when treating an entire tank, carbon filters/pumps should be disconnected, because it can remove beneficial nitrifying bacteria. After treatment is completed, 30% to 50% of the water in the tank should be changed.  Hospital tanks should be thoroughly cleaned after each isolation.

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Recommended! A-Z of Tropical Fish Diseases and Health Problems: The aim of this book is to help aquarists recognize signs of illness so they can identify and resolve problems. Divided into three sections, the first focuses on health and husbandry, describing the signs of a healthy fish, anatomy and general care; the second provides signs of diseases and health problems and is cross-referenced to section three, which covers the treatment of diseases and health problems. Illustrated throughout with top-quality color photos, the book is an invaluable reference for novice to experienced fishkeepers. Click here for your copy.