Skip to content


How to Perform an Emergency Fish-In Cycle

by Rahim Mohamed 06 Jun 2024

Performing an emergency fish-in cycle is necessary when fish have already been added to an uncycled tank. This process can be stressful for the fish, so it's crucial to take measures to minimize harm. Here are the steps to perform an emergency fish-in cycle:

1. Test the Water

  • Frequency: Test the water daily.
  • Parameters: Focus on ammonia, nitrite, and nitrate levels.
  • Tools: Use a reliable liquid test kit for accurate readings.

2. Partial Water Changes

  • Frequency: Perform 20-30% water changes daily or every other day.
  • Preparation: Use a dechlorinator to treat new water before adding it to the tank.
  • Purpose: Dilutes harmful ammonia and nitrite levels.

3. Use a Water Conditioner

  • Product Recommendation: Use a conditioner like Seachem Prime.
  • Function: Detoxifies ammonia and nitrite temporarily, reducing their toxicity.

4. Add Beneficial Bacteria

  • Product Recommendation: Use commercial bacterial supplements like Seachem Stability or Tetra SafeStart.
  • Purpose: Introduces beneficial bacteria to help establish the nitrogen cycle more quickly.

5. Feed Sparingly

  • Frequency: Feed only once or twice a day.
  • Amount: Provide small amounts that the fish can consume within a few minutes.
  • Purpose: Prevents uneaten food from contributing to ammonia spikes.

6. Monitor Fish Behavior

  • Signs of Distress: Look for gasping at the surface, lethargy, loss of appetite, or unusual behavior.
  • Immediate Action: If distress is observed, perform an additional water change and check water parameters.

7. Be Patient

  • Timeline: The nitrogen cycle can take several weeks to fully establish.
  • Consistency: Regularly monitor water parameters and adjust as needed.
  • Long-Term Care: Continue with frequent water changes and bacterial supplements until the cycle is established.

Tips for Success

  • Aeration: Increase aeration using an air pump and airstone to ensure adequate oxygen levels.
  • Low Stocking Density: Keep the fish population low to reduce waste production.
  • Use Live Plants: Consider adding live plants, which can help absorb ammonia and nitrite.
  • Avoid Chemicals: Do not use harsh chemicals or medications that can disrupt the cycling process.


While performing an emergency fish-in cycle is not ideal, following these steps can help minimize stress and harm to your fish. Remember, the best approach is always to cycle the tank before adding fish, but in emergencies, these measures will help establish a healthy environment for your fish.

Prev Post
Next Post

Thanks for subscribing!

This email has been registered!

Shop the look

Choose Options

Recently Viewed

Edit Option
Have Questions?
Back In Stock Notification
Product SKURatingDescription Collection Availability Product Type Other Details
Terms & Conditions
What is Lorem Ipsum? Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum. Why do we use it? It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content here, content here', making it look like readable English. Many desktop publishing packages and web page editors now use Lorem Ipsum as their default model text, and a search for 'lorem ipsum' will uncover many web sites still in their infancy. Various versions have evolved over the years, sometimes by accident, sometimes on purpose (injected humour and the like).
this is just a warning
Shopping Cart
0 items