How to Make Zug Jars

Use your zug jars to incubate fish eggs in a safe environment.

In the field of ichthyology and fish stocking, it is sometimes necessary to incubate fish eggs outside of the mother and in a laboratory setting. This requires the use of zug jars as a way to simulate the natural setting of the eggs. Zug jars used for scientific purposes are heavy duty and made of thick glass, but if your goal is to incubate fish eggs at home, you can create zug jars using simple household items.

Things You'll Need

• 2-liter soda bottle
• Rubber or plastic tubing with valves
• Water fountain motor
• Metal or wood vertical wine rack
• Bucket

Instructions

1. Cut the bottoms off a 2-liter bottle so there is a large hole. Place the bottle upside down in the metal rack so the part where the soda pours out is on bottom and the cut bottom is on top.

2. Place the motor in the bucket directly under the bottle.

3. Place one end of the rubber tubing on the bottle's pour spout and the other end on the motor.

4. Put water in the bucket and turn on the motor.

5. Check the valves at the motor and the opening of the bottle to make sure you can control the flow of water into the bottle. The proper flow is imperative to creating a proper incubation environment.

6. Place the eggs in the zug jar once it has been filled; they will settle to the bottom.

7. Replace the water in the bucket every day to make sure the eggs are getting the optimum level of oxygen. Keep watch until they are near hatching, which could be as long as two months, according to Food and Agriculture Organization of the United Nations.

Tips & Warnings

• Make sure the water used for the eggs is at room temperature and has the correct acidity level for the incubation.

• The motor will propel the water into the bottle and slowly begin to fill it. When it reaches the top, the water will overflow and go directly back into the bucket. The flow of water provides a constant flow of oxygen to the eggs and mimics the incubation atmosphere of the wild.

References

• New Mexico State University: New Mexico Aquaculture
• Food and Agriculture Organization of the United Nations: Incubation of Fertilized Eggs