As spring slowly but surely turns to summer, it is important to be mindful of how weather affects fish. As temperatures rise, dissolved oxygen levels in the water decrease. Without adequate oxygen, your fish are left vulnerable to a fish kill event.

One of the most important ways to avoid a fish kill is through aeration. Aeration helps to keep oxygen levels steady, and reduces the chances of a sudden inversion, or an “averaging” of the oxygen levels at different depths. For a more detailed explanation of how this can happen and the important role that aeration plays in stopping this, read Avoiding Summer Fish Kill.

Another important thing to be cautious about however, is feeding your fish. Fish use extra oxygen during the digestion process, so if oxygen levels are already low, feeding can cause a drop to dangerous levels and potentially leave you with dead fish.

When Should I Feed and How Much?

Fish can actually survive for quite some time without food, so the simplest strategy is to look at the forecast and pick the coolest days to feed. Of course, during the summer you may have weeks of hot weather with no break in sight. When that is the case, and you know that your lake or pond cannot support its fish population without supplemental feeding, feed early in the morning, and feed less than normal. Early in the morning, while the temperature is still relatively cool, the oxygen levels in your pond are going to be at their highest. This makes it the safest time to feed. Just be mindful of the amount, making sure that you are feeding at a rate of only 50-75% of your normal amount, depending on the predicted temperature, and whether or not there is a supplemental supply of oxygen.

If your water is properly aerated, it is significantly less likely that a fish kill event could happen. Although it is always important to be cautious in hot weather, especially when there is a dramatic fluctuation in temperature, continuing to feed more normally is far less dangerous.