Stress Zyme

From The Aquarium Wiki
Jump to: navigation, search
Stress Zyme.jpg

What is it?[edit]

Stress Zyme is a commercial bacterial bottle made by API to add beneficial bacteria that speeds up the break down of dead plant material, fish waste, uneaten food and other organic material in a aquarium tank.

  • The bacteria is kept in a special suspended state so it requires little food for the long time it is in the bottle.[1]

What is in it?[edit]

Believed to contain six species of waste control bacteria species.


By adding this product weekly you are breaking mulm down with large amounts of known harmless bacteria and it therefore prevents the growth of disease causing bacteria like Aeromonas, Pseudomonas or Flavobacterium columnare, etc. by starving them of available food. This means that fish have less bacterial caused diseases.

  • Less ammonia given off from decaying mulm.
  • Keeps the amount of mulm building up on the filter media down so the filter can keep running longer before requiring maintenance cleaning.
  • Substrate looks cleaner and requires less vacuuming and cleaning.

What doesn't it do?[edit]

Unfortunately a lot of forum web sites seem to think it contains nitrifying bacteria species. It does not. So not surprisingly it does not speed up the nitrogen cycle process.[2]

API claim it 'speeds development of the biological filter'. This is often taken to mean it speeds up the cycle process, API mean it reduces mulm collecting on the filter media therefore increases availability of oxygenated water to the nitrifying bacteria. More oxygen, more growth of nitrifying bacteria.

Tips for keeping it[edit]

  • Store this product at a cool temperature. Ideally in a fridge at ~5-10°C (41-50°F) and it will last for years.
  • Do not let it get frozen or above 45°C (113°F) or the bacteria inside will die.
  • Check the expire date on the product before purchase to ensure you have a product which will last for five years.

Tips for using it[edit]

You can't overdose this product, unless your tank is very small (less than 25 Litres (6.6US G.) say), so add double dosages weekly for the first month to reduce mulm and possible harmful bacterial presence faster.

  • Don't expect miracles, bacteria work slowly. You should notice improvements after a month.
  • Shake the bottle before use.

Where to get it[edit]

This product is easy to obtain from any good aquarium shop in the High street or online.


  1. Process for producing an aqueous suspension of nitrifying bacteria by Bock, Eberhard (Hamburg, DE) - US Patent 4874707
  2. Method of using ammonia-oxidizing bacteria by Hovanec, Timothy A. (Moorpark, CA, US) - US Patent 7482151. See Table 14