The Use Of Beneficial Bacteria For Water Quality Control In Koi Ponds

(Bio-Augmentation)

BY FERNANDO IBANEZ
AKITA KOI NATURAL GARDENS
357 Channing Way, Alameda, CA 94502
TEL: 510-864-7011
EMAIL:ibanezaquatics@aol.com

Throughout the years that I have been involved in the aquaculture industry, one of the problems I have seen with the greatest impact on the health and well being of fish, whether koi, ornamentals or food fish, has been the problem of maintaining good water quality of the pond, tank or reservoir where the fish are kept. We know that there are three major components or contributors to good healthy koi: environment, feed and low exposure to infecting organisms that can produce disease. It is very important to maintain a balance of these three components if we want to enjoy our fish for a long time. When speaking about environment I refer to all the physical and chemical conditions of the pond. Feed is the specific nutritional requirements of fish and low exposure to disease is the prevention of foreign organisms that at one point can infect and damage or kill precious and expensive fish. If one is to maintain only two of these components in good operation but one is deficient, for example food quality and quantity is appropriate and the exposure to dangerous organisms is very low, the fish will possibly be stressed and barely surviving. In contrast, if we don’t have control over two of these components we will experience heavy losses and difficulties. In this article I will deal with the problem of water quality and specifically with the use of bacterial products that can help us maintain better water quality in an inexpensive and almost effortless manner.

We all know that when we maintain fish in closed re-circulation systems, with very little water exchange, water deterioration will occur with time. This occurs more so with constant addition of nutrients through feed, run off, leaves and other materials that can fall in the pond. All these contribute to the decomposition of organic mater and as it dissolves in the water or is consumed by the fish, it is subsequently metabolized. This process results in settable and un-settable solids, nitrogen compounds and phosphorous compounds that create an accumulation of organic material and toxic chemicals. In addition to the fish, algae, bacteria and other microorganisms begin to grow and multiply rapidly using this material as food. The organic material accumulates and the chemicals such as ammonia and nitrites soon surpass toxic levels, especially as the density increases due to growth or addition of more fish to the pond. High concentration of these nutrients will favor the development of massive blooms of algae that not only affect the transparency of the water in a negative way but also can reach such numbers that will contribute to massive “die-offs” depleting all the oxygen available and causing high mortalities. This high concentration of nutrients can also contribute to the development of filamentous algae that will soon cover rocks sidewalls and can even get into the pipes, pumps and filtering systems rendering them useless or less efficient.

The use of beneficial bacteria populations that can decompose organic sludge as well as bacteria that can convert ammonia and nitrites into nitrates, reduce BOD (biochemical oxygen demand), bind excess phosphates, prevents algal blooms and maintains a microbiological equilibrium in the pond. This process has been studied for many years in the water treatment industry and recently has been introduced in aquaculture with very encouraging results. For the koi enthusiast it is important to make sure that all of these functions are performed in the pond and unfortunately the commercial manufactures of these products have failed to make a complete source of all the bacteria needed for good water quality maintenance.

When looking for a product that can accomplish all of the above make sure it contains the following list of bacterial types:
• Aerobacter aerogens:
Under aerobic conditions, these bacteria oxidize the carbohydrates and short organic acid chains to carbon dioxide and water. When oxygen is limited, Aerobacter aerogenes ferment the carbohydrates in order to produce short-chained organic compounds, carbon dioxide and water. The short chained organic compounds serve as fountains of carbon and energy for other bacteria such as pseudomonas sp.
• Bacillus subtillis:
These bacteria oxidize carbohydrates, organic acids and other compounds such as fats, oils, proteins and starches. B. subtillis is particularly active and beneficial in sediments because it can excrete enzymes into the sediment that function to degrade the organic fraction. They are active denitrifying bacteria, which means they take nitrate and convert it to nitrogen gas.
• Cellumonas biazotea:
Convert cellulose to soluble carbohydrates, which serve for growth of C. biazotea and other bacteria.
• Nitrosomonas:
Oxidize the ammonium nitrogen to nitrite in the presence of dissolved oxygen and their activity is restricted by the presence of soluble organic compounds in quantities greater than 20 mg/l. These bacteria are very effective at binding orthophosphates and helping prevent excess algae blooms.
• Nitrobacter:
Oxidize nitrite to nitrate nitrogen. These also require aerobic conditions and their activity is inhibited by the presence of ammonium. They are very effectively binding orthophosphate and helping prevent excess algae blooms.
• Pseudomonas denitrificans and Pseudomonas stutzeri:
Reduce the levels of nitrate nitrogen under anaerobic conditions. Their principal function is to oxidize the soluble organic compounds.
• Rhodopseudomonas palustris:
Use the energy of light in order to oxidize organic compounds photobiochemicaly. Under anaerobic conditions, they perform denitrification.
Until now solutions to the problem of excess algae build up and water quality deterioration have been elusive and limited to expensive manual cleaning and dredging or use of dangerous or toxic chemicals. Finally an environmentally friendly solution is available. Live bacteria cultures of the right type can provide a convenient, cost effective treatment for even the toughest water restoration projects.