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How to Make Infusoria for Fry (Baby Fish)


I have raised numerous baby fish and enjoy sharing my experience with other aquarists. I love all types of pets.

Learn how to make this nutritious food for your fish fry.

Learn how to make this nutritious food for your fish fry.

What Are Infusoria?

When raising small fish fry, the first challenge you'll run into is the one that involves feeding invisible food to invisible fish. The first kind of food young fry of small fish species need is called infusoria. 'Infusoria' is a term that refers to microscopic life forms such as protozoa that live in fish tanks, though not usually in large enough numbers to sustain a few hundred hungry baby fry.

Why Do Small Fry Need to Eat Infusoria?

Infusoria are essential for small fry such as betta fry and guppy fry, as new free-swimming fry are simply unable to feed on other live foods. Even baby brine shrimp and micro worms may be too large for small fry. A good supply of infusoria will help your fry through the first vital days of their lives and make sure that their stomachs are always full.

An infusoria culture.

An infusoria culture.

How Do I Culture Infusoria?

So, as a responsible breeder, you will need to culture infusoria for your fish fry. You should do this 3–4 days before you expect the fry to hatch as it takes 3–4 days for the culture to really take off.

  1. For starters, you'll need some tank water. It's good if you have an established tank that likely already has significant numbers of microscopic lifeforms living in it.
  2. Add to the tank water some organic food, such as cut grass, a rabbit pellet, or blended lettuce.
  3. Make sure that the culture has easy access to oxygen, and place the jar in a sunny spot.
  4. Over the next three to four days, you should see the water go cloudy and then clear once more. You will want to wait until the water has cleared, as this is the sign of a successful and 'clean' culture.
  5. Once you have clear water, add a little to your tank to feed your fry.

Methods of Incorporating the Culture Into the Tank

How you add the infusoria to the tank depends largely on your personal preference and what works for you.

  • Some people recommend a slow siphon method that supplies a constant stream of fresh infusoria into the tank.
  • Others recommend simply tipping half the culture into the tank. This is slightly more risky.

In either case, it's important to ensure that the organic matter does not end up in the tank. Then you'll simply have rotting organic matter in your fry tank, which can cause all sorts of problems.

What About Liquifry?

Liquifry is a product that feeds the infusoria in the tank and promotes the growth of the small organisms that fry feed on. Many breeders swear by liquifry, although buyers should be aware that it is not so much fish food as it is food for the fish food.

The Benefits Outweigh the Risks

Be aware that it is potentially possible to introduce nasties to your tank by carelessly making infusoria. Bacteria and some non-friendly biological organisms such as dragon fly larvae can be a problem.

However, I have found that, if properly managed, the risk of problems is far outweighed by baby fish which have fed well in the first few days of their lives. Stunted fry are frustrating and demoralizing to raise and may never do as well as their better-fed counterparts.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.


Sridevi on September 09, 2018:

Hi ! Do we need to close the jar with a small holes cover. This is the 1st time doing infusoria. Pls advice. Its a week I started infusoria but not able to see b'coz I don't have microscope instrument. Pls help.

britaney on June 01, 2013:

You may want to keep it open for the oxygen to get into the jar

Jay on February 03, 2012:

Do we need to close the jar or cover it with nail holes sheet? please advice...

fishguy on December 31, 2011:

probably from the grass

vidar on October 30, 2011:

How do dragonfly larvae get in?

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