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A Brief History of the Infusorian Culture

Humphry Axelbearing

In the beginning there was scum! By some divine miracle, a few such bits of organic scum came together to produce the precursors of all life on earth. The existing organisms that best represent our slimy origins, may be collectively referred to as the "Infusorians". Single-celled, and propelling themselves with cilia, the protozoa are one class of such creatures, and the representative of this group we will discuss in the present column is the king of protozoans, the incredible, the fantastic, just returning from a tour of the greatest swamps in the world, put your cilia together and give it up for the one, the only, the majestic paramecium!

Culturing Paramecia:

The paramecium is near and dear to the hearts of may fish enthusiasts due to several key characteristics - They are large enough to see without magnification, damned easy to culture, and readily eaten by even the smallest of killie-fry! Paramecium can be cultured in any vessel that will hold water, whether it is a 2-liter soda bottle (perhaps my favorite container) or the toilet bowl in a South-American prison cell (definitely my least favorite wink. Whatever container you choose, in order for paramecia to flourish, you must create an ecosystem that provides the basic needs of the organism (i.e. nutrients, water quality, etc.). I eschew (geschuntite!) the need for sterile lab technique and do not worry about contamination of cultures with other organisms of infusorial heritage. In my experience, a healthy population of paramecia will literally out-eat and out-reproduce any invading organisms that cannot swallow them whole. In fact, if you have a hard time finding a "pure" paramecium starter culture I recommend starting with a pint of water from any aquarium that contains live plants. Siphon up some of the detritus (Latin for rotting brown junk) in the bottom of the tank and treat it as a starter culture. Initially you will probably have a dozen or more different infusorial species, but by the time you have sub-cultured twice, paramecium will be the dominant (if not the only) species remaining! The health and vigor generated by random reproduction, is another advantage to culturing "native" infusoria rather than one of the pure cultures you can get from a biological supply house. Native organisms are already adapted to your water conditions, and have not been weakened by many generations of line breeding from single individuals. In other words, they will be much more likely to thrive and multiply in your fishroom!

My standard method (which up till now was a carefully kept secret, known only to a few hundred of my closest killie keeping colleagues!) is a three step process. The first step is to set-up the food chain. Fill a 2-liter bottle 3&Mac218;4 full of clean aged tap water, and add one chunk of Purina Dog Chow and 2 square inches of dried iceberg lettuce. Leave this bottle overnight (12-24 hours) uncovered, thus creating a bacterial bloom. I have tried many different sources of organic matter to start paramecium cultures and nothing even comes close to matching dog food for initial population growth. I think it is because dog food contains a complex combination of nutrients (proteins, fats, vitamins and minerals) that are not always present in adequate amounts in traditional culture media (i.e. hay, peas, soy flour, dried lettuce, oatmeal, etc). I am sure other brands of dog foods are probably adequate for these purposes, although you will need to adjust for the size of the pellets (PDC chunks are spherical and about 1&Mac218;2 inch in diameter). I do not recommend adding dog food to an older culture, however, because it can cause a bacterial bloom so intense that the culture goes anaerobic and the paramecia literally suffocate producing a smell rivaling that of a microworm culture gone bad!

Step two is to add the starter culture (about a cup of a thriving paramecium culture) and cover the bottle loosely - I just set the cap on the bottle. It will take approximately 6 -10 days for the bacterial cloud to clear, but when it does you will have millions of paramecia. I feed my fry tanks directly from the culture bottle with an eyedropper, but only when the culture is clear. I am in the habit of making paramecia available to all my fry for the first week after they hatch. Obviously many killies are large enough to eat other foods and do not absolutely need paramecium as a first food. However, the way I see it, the paramecia are available 1 swim around and eat bacteria in the fry tanks a no-lose situation!
Step three is maintaining the population… At first the paramecia are thick in the container, but a week or so after the bottle has cleared you will notice a decline in the population density. That is because the when there was an abundance of food (bacteria) the paramecia grew and multiplied. The population growth is exponential, and the paramecia rapidly exceed the available food supply.

 Eventually the paramecia and bacteria will reach a balance point, where the population level can be sustained by the available food. So, if you want to keep the paramecia population up, you have to keep the bacteria up as well i.e. you have to keep feeding the bacteria. I suggest adding 8-12 rolled oats (old fashioned Quaker Oatmeal), about once a week. You can vary the amount, and the frequency of feeding, to maximize population density. Another tip is to add a couple snails to the culture (after it clears initially). Snails eat excess food and their waste products encourage bacterial growth. The bottom line is that cultures with snails will consistently out produce those without snails! Eventually the waste products of metabolism will accumulate to the point of toxicity where the population does not revive upon re-feeding. I can usually keep a culture going strong for 2-3 months before the inevitable decline. The worst case is when the culture "goes bad" (hold your nose as you pour it out) and you have to start over. One way to assure a constant supply of paramecia is to keep at least 3 cultures going all the time - dumping the oldest of the 3 existing cultures and starting a new culture each month. That way if one culture goes bad, or you overfeed and a culture gets cloudy, you will probably have at least one other clear culture from which to feed or start a new bottle. By the way, an old culture need not go down the drain, so to speak - instead dump it into your daphnia culture, or use it to water your house plants! Next month I will present another use for the nutrient rich water in an old paramecium culture!

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