If you’ve sought information about feeding the newly hatched fry, you’ve probably been told to go out and get some infusoria. What is infusoria, where do you get it, and what do you do with it once you have it?
At one time, infusoria referred to just about any microscopic, or nearly microscopic, organism that lived in freshwater. That meaning is arcane in the scientific community, but the term infusoria is still used by many within the aquarium community, even by younger fish enthusiasts.
To aquarium enthusiasts, infusoria refers to many small organisms in water that tiny fry can feed up upon. There’s a large number of organisms that could be in an infusoria culture; here are some of the primary ones include:
Infusoria is particularly critical for anyone who is attempting to breed fish, as many newly hatched fry subsist entirely on microscopic infusoria during the early days of their lives. Having a ready supply of infusoria can make the difference been success and failure for an entire hatching of young fry.
Infusoria live in a watery environment and can be found everywhere. Purified water purchased in bottles at the store is relatively free of such organisms. Outdoor bodies of water are at the other end of the spectrum, and they are generally teaming with many types of microscopic organisms. Even puddles water by the roadside are full of infusoria.
Like other bodies of water, aquariums also have infusoria; however, the quantities are usually not sufficient to support newborn fry. Thus, aquarium owners must grow their own cultures if they want to have enough infusoria to feed their newly hatched fry. The items needed to culture infusoria are pretty common, easy to find, and don’t cost an arm and a leg. However, before delving into starting your own infusoria culture, it’s wise to know where not to get infusoria.
It is not unusual for aquarists to trot down to the nearest pond and scoop up some water to get a good starter culture for infusoria. However, that practice brings considerable risk. The unknowing aquarist in all likelihood is carrying home considerable grief in that little jar of pond water.
In nature, there are often some undesirable elements hanging out with the good stuff. Water tigers, the larvae of the diving beetle, are particularly prolific and quite nasty. They’ll eat anything they can get ahold of, including your young fish. Even bugs considered beneficial, such as the water boatman, can be dangerous to small fry. The list of undesirables abound, but the short list includes these common critters:
Needless to say, the dangers outweigh the benefits when it comes to taking water from outdoor sources to start an infusoria culture. Instead, the best option is to start your own culture indoors using your own items so you can control what is in the end product.
Home culturing of infusoria is relatively easy and inexpensive. A multitude of methods exist, but the basics are all the same. Take water with organisms in it, such as your aquarium water. Add some nutrients such as blanched lettuce, to promote the growth of the infusoria. Wait for the infusoria to grow, then feed to the fry. The nutrient material can range from lettuce to commercial preparations such as Liquifry. The key element is to ensure all materials used are free of pests that might harm the young fish fry. Some of the many things aquarists have successfully used to create and maintain infusoria cultures include:
The container used (usually a jar) should hold several quarts to a gallon of water. Ice cream buckets can work as well. Aquarium water is generally the best source for the water, but tap water can also be used. Some aquarists have even used the old water from a flower vase, as it is usually well populated with infusoria. Add the nutrient medium and let the whole soup cook in sunlight for several days.
As the infusoria grow, the water will become cloudy and in some cases, movement of the infusoria can be seen with the naked eye. Examination of a drop of water under the microscope will confirm the growth of the infusoria. Some aquarists will start more than one culture to allow them to be harvested at different times. With a little practice, it is possible to keep the culture going for extended periods of time.
Using the culture is quite easy. Simply siphon off a portion of the cloudy water, taking care to avoid sucking up pieces of the decaying nutrient material. Drop the infusoria-laden water into the tank with the fry to give them a tasty meal. Tiny fry requires frequent feedings of infusoria until they grow large enough for other foods, such as freshly hatched brine shrimp or commercially prepared fry food.