THE MOST IMPORTANT FACTOR AFFECTING FISH HEALTH!
If a fish is diseased, the first factor to check is water quality.
Minimum test kits that a pond owner should use to test pond water:
- Ammonia Test Kit
- Nitrite Test Kit
- Nitrate Test Kit
- pH Test Kit or Electronic Probe
- Total Alkalinity (Not Hardness)
Levels that would be “ideal” for each test:
- This is complex and can vary under different conditions.
- The following general guidelines are useful*:
- Ammonia is highly toxic to fish so when any level is detected, action needs to be taken right away.
- Nitrite presence above 0.2 ppm (a very low level) is also of concern and needs to be addressed right away.
- Nitrate presence is not uncommon in ponds but levels above 80 ppm can make fish more vulnerable to disease.
- pH should be above 7.0! A “crash” in pH (i.e. a rapid lowering) is very deadly to fish! That is why a buffering agent is very important in a pond.
- Total Alkalinity should be above 30 (which is the very low end of the scale) and ideal is 120. We will probably not accomplish the ideal but should be in the 60 or higher range.
Please refer to the Information Sheet on the Nitrogen Cycle to gain more understanding of where Ammonia comes from, how it is converted to Nitrites and then Nitrates, and how pH and other factors can affect the presence of these materials.
- Nitrates are an end product of the Nitrogen Cycle and serve as the primary food source for plants that take their nutrition out of water. Growth of algae in your pond is a good indicator that Nitrates (and Phosphates) are present (and that the Nitrogen Cycle is going to completion). If you don’t want algae growing in your pond you need to have enough water plants in the pond to use the Nitrates so that there is not enough left for algae to grow.
- Floating plants are very good additions to your pond during the summer to reduce Nitrates and Phosphates (high levels of which can also cause the “tea” color in your water). The five most efficient floating plants are Water Hyacinth, Parrot’s Feather, Azola, Water Lettuce, and Duck Weed.
- pH can be kept high (about 8.3) when plenty of Carbonates are in the water. Carbonates can come from rocks and gravel (such as river rock) in your pond. Plaster of Paris (pure) “pills” can also help buffer water to keep the pH from “crashing.”
*See individual Information Sheets on correcting water quality problems as well as the one on the Nitrogen Cycle.