Culturing infusoria is common practice for most aquarists attempting to breed small species of fish, which is used to provide a source of live food for a newly hatched fish fry that is typically too small to feed on commercially available foods.
The fish fry’s natural instincts are to eat microorganisms moving within the water column, even if commercial foods were crushed into small pieces, they may not necessarily learn to feed off an inert source of food.
What is Infusoria?
Infusoria is comprised of single-cell organisms within three distinct orders: Flagellata, Ciliata, and Tentaculifera. In the past, infusoria was applied to all microorganisms found in water, including Diatoms, Rhizopoda, and Rotifera.
They are found in all bodies of freshwater or saltwater oceans, seas, lakes, ponds, rivers, and streams. Infusoria are identified by their cilia or hair-like appendages which allow them to swim and help them obtain sources of food.
Infusoria reproduces much quicker in warmer temperatures, ideally at temperatures between 24° Celsius (75° Fahrenheit) to 28° Celsius (82° Fahrenheit), an aquarium heater while culturing infusoria in chilly rooms may be required.
Infusoria must be cultured in conditioned water, tap water contains chloramines that are not only harmful to fish but to infusoria as well, capable of decimating a culture.
There are numerous methods used to culture live infusoria, we will review three popular methods that are tailored for short-term or long-term use while keeping it simple.
Culturing Infusoria with Yeast
The first method is the quickest and easiest, it also does not produce a strong odor similar to the other two methods. If your aquarium inhabits prolific breeders and you notice unanticipated fish fry swimming around, this method will allow you to rapidly culture a source of food within two days.
Culturing infusoria with yeast requires a glass jar without a lid between 1 – 4 liters, non-fortified powdered yeast, a teaspoon, and a running aquarium with an installed filtration unit that is fully cycled.
Fill the glass jar with matured aquarium water and then remove the charcoal or foam filter from your filtration unit, gently squeeze excess water into the jar. Matured aquarium water and filters are home to small quantities of infusoria but the filtration unit and fish hinder their population growth, unlike a culture of infusoria that freely reproduce.
Mix a quarter teaspoon of yeast into a cup with matured aquarium water, just enough water to thoroughly mix the yeast, and then pour the mixture into the jar. The yeast will act as a source of food for the infusoria, this culture will require a quarter teaspoon of yeast each day to sustain itself. Within two days you’ll begin to notice a concentrated culture of infusoria swimming around.
Culturing Infusoria with Java Moss
This method is a long-term and self-sustaining setup that is most suitable for those who have community tanks with prolific breeders and are constantly rearing fish fry. Culturing infusoria with java moss is capable of sustaining itself for several months or more (4 – 6 months).
You’ll only need three ingredients: A bucket with a lid, java moss, and matured aquarium water. Simply fill a 5-gallon bucket halfway with matured aquarium water, then add enough java moss equal to 6 inches deep.
Store the bucket in a warm area with the lid fastened shut and within a week, a large colony of cultured infusoria will be readily available. The only maintenance required will be occasionally topping up the bucket with matured aquarium water whenever the water levels drop due to evaporation.
Under these no-light conditions, the java moss will not completely die. Instead, it simultaneously grows while rotting at the same time to produce enough food for the infusoria.
Culturing Infusoria with Vegetables
Infusoria can be cultured by soaking any decomposing vegetative matter such as Brussel sprouts, lettuce, spinach, broccoli, and potatoes. Using this method, a culture of infusoria will start to proliferate in two to three days, depending on the amount of sunlight and temperature.
Each vegetable will need to be blanched just to soften them up for the infusoria. First, start by boiling a pot of water and then select any vegetable that you’d like to use, place the vegetable into a bowl of boiling hot water and let simmer for 5 – 8 minutes.
Drop a few pieces of vegetables into a glass jar that has been filled with matured aquarium water, then add a small piece of a floating plant such as riccia, duckweed, mosquito fern, or water hyacinth.
Note: This method requires an open jar without a lid and if a lid is being used, it must be perforated.
These plants will introduce a small culture of infusoria into the glass jar that will begin to rapidly proliferate. The water will begin to turn cloudy due to a rise in bacteria that eventually dissipates once the infusoria consumes them.
During this process, a strong odor is present during the first few days while the vegetation is decomposing. Store in a warm area under direct sunlight, ideally within a shed or garage that can handle the odor.
How to Feed Fish Fry with Infusoria
If you’ve created a culture of infusoria using decomposing vegetation or yeast, simply use a liquid dropper to siphon the infusoria. First, gently mix the jar by tilting it a couple of times and it’ll create a whirlwind of infusoria swimming into the center of the jar.
Try not to siphon in any of the decomposing vegetation or yeast which may foul your aquarium’s water. To prevent too much yeast from being siphoned, collect the infusoria prior to adding the daily teaspoon of yeast.
If you’ve created a culture of infusoria using java moss, simply use a small cup to scoop water from the surface of the bucket. The culture of infusoria is densest at the surface, try not to mix the water prior otherwise it may send the infusoria to the bottom of the bucket.
A healthy culture will contain millions of infusoria, feeding fish fry with one cup from the java moss culture (250 ml) or 50 – 100 ml from the liquid dropper will suffice in most cases.
Fajar Nurul Arifah, Roffi Grandiosa, and Fittrie Pratiwy. International Journal of Fisheries and Aquatic Studies 2021; 9(1): 131-134 The enrichment of live feeds: An inquiry for feeding at early stages of fish. Jan 2021