The Garden Pond: Summer at Last!

Summer is a great time for the pond enthusiast. For the most part, he can pull up a lawn chair, sip a cup of ice cold lemonade, and just sit back and enjoy the fruits of his labor. There are, however, a couple of items to consider.

Give ‘Em Air

The warmer that water gets, the less oxygen it can hold. At the same time, the fishes’ metabolism increases, so they need more oxygen than ever. This presents no problem for a few small fish in a large pond, but in the more common, crowded pond, dissolved oxygen can easily become depleted. As the levels drop, fish suffer stress that can lead to disease, and in the worst case scenario, can become asphyxiated. While it’s thankfully not a common occurence, some hobbyists have lost whole ponds full of fish overnight under extreme conditions.

The situation can become even more critical if the fish are overfed, or if there is a great deal of decaying debris in the pond, since the microscopic organisms that decompose waste also consume oxygen. Some fish medications, especially those that contain formalin, also chemically remove significent amounts of oxygen from solution.

And if all that isn’t enough, so-called “oxygenator” plants and submerged algae also contribute to the problem. It’s commonly understood that all live plants consume carbon dioxide and actually produce oxygen via photosynthesis, but that only occurs during the daylight hours. At night, when there is no energy from sunlight, plants consume oxygen just as animals do.

There are a few things the pondkeeper can do to assure the safety of his fish during the warmer months:

  • Aerating devices, particularly water fountains and waterfalls, should be kept operating at maximum performance – especially at night or if medication is added. Extra pumps are highly recommended.
  • Excessive amounts of debris and algae should be removed.
  • Feed fish carefully; several smaller feedings per day are better than a single large feeding. Remove uneaten food promptly.
  • Thin out the fish population if necessary. It’s far better to have fewer, but healthier fish.
  • Small, frequent water changes can reduce the amount of chemicals and microorganisms that consume oxygen.

Special Summer Feeding

Since their metabolism is in high gear, most pond fish benefit from feedings of high-protein “growth” foods during the summer months. This is the time of year when fish are growing rapidly, developing color, and beginning to store body fat to get them through the long winter, so good nutrition is important.

As always, it is better to feed several small feedings per day, instead of a single large feeding. Fish naturally tend to graze all day, rather than to gorge themselves for ten minutes, then waiting 24 hours until the next meal. It’s also best to introduce unfamiliar foods slowly, possibly by mixing it in with their standard diet at first. Uneaten food creates unhealthy conditions, as seen in the previous section.

Plant Chow?

Plants are also in high gear during the summer months, cranking out luscious foliage, creating beautiful blooms, and in the case of some of our winter-hardy varieties, storing energy in tubers or rootstocks. In order to perform all these biological duties, plants require a handful of major and trace amounts of minor elements. If even one of these elements is exhausted, the plant will suffer, and if denied for too long, the plant may perish.

This is a particular problem for rapid-growing, heavy-feeding plants like water lilies, some rushes, cattails, and irises that are commonly kept in pots. By midsummer, these plants may have consumed all the limited resources in their pots, and basically appear to “run out of gas”. New leaves may come in deformed or discolored, older growths may wither rapidly, and blooms may become disappointingly few and far between.

If plants begin to show any of these symptoms, the addition of fertilizer tablets may well get them back into shape. The better brands are time-release formulas that reduce risk of burn, and are simply poked into the pots a few inches from the plant’s base.