API Stress Zyme + 16 oz.

SKU: 199616
Manufacturer: API
MPN: 56E

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Stress Zyme improves the development of your biological filter and helps keep a naturally balanced aquarium. Contains 100 million live bacteria per teaspoonful. Continuous use of Stress Zyme assures a healthy biological filtration, good water quality and a clean aquarium. Treats up to 960 gallons. It is safe for freshwater and saltwater fish, invertebrates and plants. Stress Zyme is restricted and will not be shipped to Hawaii.


Package Size16 oz.
Treats up to960 gal.
Internal Id

State Restrictions


Non pathogenic bacterial cultures


Use API dosing cap included with bottle. To maintain a clean, healthy aquarium: add 1 tsp. (5ml) per 10 U.S. gallons weekly. For new aquariums, to help boost the biological filter: double the dose, use at start up, and for 2 additional weeks.

Ratings & Reviews

6 reviews

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stress zyme


this is the best in the world i use it when i do all my water changes ,i recommend this product



Along w/ Stress Coat, I use them in the spring water and tapwater, for every 20% weekly water change in all of my F/W tanks. Also use them both in the water bowls for my PDFs and their tads.



this works great. i ran out of stress zyme during a water change once and my water got really murky and filthy looking! i ordered 64 oz of stress zyme after that! great to use with stress coat! definitely recommend this!

Happy Fish = Happy owner


I began using Stress Zyme when using Stress Coat. Honestly, I don't know what I expected, since this came as a recommendation from some trusted guys at the local fish shop. Ever since, my aquarium water has stopped smelling "fishy", except when a freshwater clam dies. I'm quite happy with the result.



Stress Zyme is essential for a healthy tank, especially for breeding. I do not want to add a supplemental slime coat when fish are healthy, and this product provides essential bacteria without also adding a slime coat.

I use this is all of my tanks, and recommend it to everyone that I give my young fish to. I highly recommend Stress Zyme.

API Stress Zyme


Add this to all my water changes and it keeps fish healthy, happy and clears the water fast. I treat my fish like they are real pets.