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(Source: C. Barton from Zebrafish Book 5th Edition)


Stage 2 of the paramecium production process.  Clean, but not sterile, paramecium cultures grown in 500-1000 ml filtered fish water or dechlorinated tap water.  These are used to make cages.


Stage 3 of the paramecium production process.  Clean, but not sterile, paramecia grown in 500-1000 ml filtered fish water. The only difference between the cage and subculture methods is that with the cage method, the paramecium population is started with a subculture and in the subculture method, the paramecium population is started with a culture.  This is done to achieve optimum population density when harvesting paramecia for use in the nursery and to produce enough culture to inoculate a large number of cages. 


The best way to determine how much food each cage will make in your facility is to prepare one cage to the proper density.  After seeing how much food each cage makes, you can calculate the number of cages you will need based on the number of fish to feed.  The proper density for concentrated paramecia, as prepared for feeding fish, should be 100 paramecia/ml liquid. 

Concentrated paramecia preparation


After rinsing, pour the paramecia into a clean container.  Fill the container with clean fish water until a concentration of 100-150 paramecia/ml is achieved.  Use this to feed.  Note: Before you feed using the paramecia, check the ammonia level with a test kit.  If it shows any traces of ammonia, repeat the 23 µm mesh straining process.

Modifications of paramecium recipe for small facilities

Small facilities may require a much smaller amount of food than the standard procedure yields. Several modifications to the paramecium production process can meet the needs of a smaller facility. 

Removing the subculture step     

One easy way to tailor the procedure to meet a smaller facility's needs, is to remove the subculture step.  Instead of using culture plates to make subcultures and then using those subcultures to inoculate a large number of cages, each culture plate can be used to inoculate up to 4 cages directly.  Remember to start enough Petri plate cultures each week to start new cultures the next week, to make food cages and to provide two backup plates.  For example, if you are making 7 plate sets, 1 will be used for new plates, 2 should be saved for backup, leaving 4 to make cages.  Four plates will make 16 cages of paramecia.

Petri dishes     

Facilities needing less than 16 cages of food per week can reduce the number of Petri plates used in each batch.  This decreases the amount of space needed for storing cultures, decreases the amount of supplies needed and reduces the amount of labor required to maintain the plates.  Making fewer plates also decreases labor because most of the ingredients and supplies require autoclaving. 

Cage size     


Figure 4.  The top drain is made using (from left to right) 90° tubing adapter (½" i.d., ½" threaded), ½" PVC ball valve, ½" male adapter, a 2" length of ½" PVC pipe, ½" bulk head fitting, ½" PVC pipe, ½" 90° elbow.  The length of the second piece of PVC pipe is determined by what size container you are using.  The elbow needs to sit directly below the center of the opening in the carboy. Cut the PVC pipe to accommodate this.  It is better to press fit the pieces together as opposed to PVC gluing them.  This makes dismantling easier when the unit needs cleaning.