For our full, in depth four page internet page Aquarium/Pond Medications page, please click on the picture below:
Including Separate pages for:
Antibiotics/Antimicrobials, Chemical & Parasite Treatments, & Organic Treatments

Further Recommended Reading:
Fish Diseases | How to Treat Sick Fish
TRUE Aquarium UV Sterilization; How to Use a UV-C Sterilizer

Aquarium Information
-A great source for current aquarium information that is updated regularly as new research become available.

Erythromycin for Aquarium Fish


Updated 1-16-19

API Aquarium, Pond, fish Erythromycin, for sale Erythromycin is a primarily gram positive antibiotic with a slightly "wider" antimicrobial spectrum to otherwise similar to penicillin.

A popular albeit often incorrectly and over recommended for fish infections. In humans Erythromycin is often used respiratory tract infections, which of coarse does not exist in fish (gills versus lungs).

During treatment Erythromycin is rapidly absorbed in a microbiologically active form into most tissues and phagocytes found in vertebrates (such as fish). Due to the often resulting high concentration of Erythromycin in phagocytes (white blood cells), Erythromycin is actively transported to the area of infection.
Over use of Erythromycin may result in muscle (including heart) and kidney damage, providing electrolytes, in particular calcium while treating with Erythromycin can aid in prevention or reversal of this damage



The primary disease pathogens for use of Erythromycin are Staphylococcus and Streptococcus (which often includes many eye and mouth infections of fish).
Occasionally these bacterial pathogens can result in fin and tail rot as well.

Erythromycin can generally be combined safely with Triple Sulfa for a more wider spectrum treatment (especially for use against Staphylococcus infections).

Another use for Erythromycin is for cloudy aquariums and cyanobacteria blooms, however Erythromycin Sulfate is much more effective for these applications (as well better for fish pathogens) and most Erythromycin (such as API) is not of this form of Erythromycin.
Sometime in 2019, "AAP Professional Aquarium Treatments" will have this preferred form of Erythromycin available for aquarium/pond use again.
Resource: AAP Professional Aquarium Treatments

Although often recommended for Columnaris and Fish Fungus, these are simply INCORRECT uses for Erythromycin.

As with ANY treatment regimen, it is extremely important to follow correct procedures that includes addressing ALL water parameters and stressors (including oxidative stress.
Please read this easy to read article and follow ALL advice given as to proper treatment regimens:
Fish Diseases | How to Treat Sick Fish

Please realize diagnostic charts are generalizations with many inaccuracies such as use for "true" mouth fungus.
Please click on the picture to enlarge for better view

FINALLY: While I strongly recommend the use of a UV Sterilizer both before and after treatment (24/7), use of this device should be discontinued during treatment with Erythromycin.

Aquarium Pharmaceuticals Erythromycin Diagnostic Chart

"API Erythromycin" can be purchased here (A business with professional aquarium medication experience dating back to 1978):
API Erythromycin

*Aquarium Medications; How They Work
*Aquarium Medications; Antibiotics, Erythromycin *

Suggested other aquarium information resources & products:

Fish Diseases, How to Treat Sick Fish
Fish Diseases | How to Treat Sick Fish

*For a proven step by step method to reduce the incidence of disease in your aquarium fish:
Aquarium Fish Disease Prevention; A Healthy Aquarium

Hydro Sponge Filter

AAP Hydro Sponge Filters

THE PREMIUM Aquarium Sponge Filter with as much as 5 TIMES the bio and mechanical capacity of commonly sold Chinese knock offs!!
Definitely worth the extra $1-3

*For Replacement UVC Bulbs to keep your UV Sterilizer (such as a TMC Vecton or Advantage UV) in peak performance, please visit this resource:
UV Bulbs

*Submersible Quartz & Digital Titanium Heaters

*Economy Submersible Aquarium, Vivarium, or Terrarium Fountain Pumps
Pumps ranging from 160, 238, 238 Gallons per Hour (gph)

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