Orange Koi fish in pond

Summer Survival Tips for Koi and Pond Fish

Summer is the ideal time to enjoy your koi and pond fish—longer days, warmer water, and increased activity levels. But with rising temperatures come challenges like oxygen depletion, algae blooms, and a risk of overfeeding. With guidance from Hikari®, a global leader in aquatic nutrition, here’s how to keep your pond healthy and your fish flourishing all summer long.

Monitor Water Temperature & Feeding Frequency

As water temperatures rise, so does your koi’s metabolism, but there is a limit most people are not familiar with. In warmer climates, pond water often exceeds 82°F consistently. As the water temperature inches toward this mark, your koi’s digestive action actually slows like it would in colder temps. At this point, switch to easily digestible diets like Hikari® Wheat-Germ Formula or Saki-Hikari® Multi-Season™, both designed to support improved digestion in warmer water conditions.

Feeding Guidelines:

  • 68–78°F (20–26°C): You can feed higher protein diets like Hikari® Gold® or Saki-Hikari® Growth up to 2–4 times daily. We always suggest smaller more frequent feeding whenever possible. This helps maintain efficient digestive action.
  • Above 82°F (28°C): Use our wheat-germ-based or multi-season diets to prevent digestive stress. Again, smaller more frequent feeding is best.
  • Always feed only what your fish consume within 3–5 minutes and remove any uneaten food after the feeding period to avoid water quality issues.

Boost Oxygen & Circulation

As your pond water temperature increases its ability to hold oxygen wanes, which can rapidly lead to stressed fish. Enhance aeration with waterfalls, fountains, or air pumps to eliminate risk. Adding shade with aquatic plants like water lilies or installing shade sails can also help lower water temperatures and reduce algae growth.

Maintain Water Quality

Regular water testing is critical during summer. Monitor pH, ammonia, nitrites, and nitrates weekly. More frequently if you see any signs of fish stress. Perform 10–20% water changes weekly to dilute dissolved solids and help improve oxygen levels. Always use dechlorinated water to avoid harming your fish or the beneficial bacteria flourishing in your pond. If you use well water, it’s a great idea to check the water parameters coming out of the well quarterly. We have had instances if high pH, nitrate and ammonia coming out of the well and negatively impacting fish.

Control Debris & Algae

Debris like leaves and grass clippings can decompose and cause oxygen depletion without you even noticing. Use pond skimmers or nets to remove surface debris regularly. Manage algae by balancing plant coverage—aim for 30–50% surface coverage with aquatic plants—and consider using a UV sterilizer or beneficial bacteria products if problems persist. Use algaecides only as a last result as they too can cause fish stress and impact water parameters.

Choose the Right Hikari® Diets

Hikari® offers a range of diets tailored for summer:

Optimal Feeding Times

Feed your koi between 10:00 AM and 4:00 PM when water temperatures are more stable. Avoid feeding early morning or late evening to prevent digestion issues during cooler periods. It’s best to avoid feeding within 2 hours of sunrise and 2 hours of sunset.

Wrap-Up: Simple Steps, Big Impact

Summer can be a highly rewarding season for pond enthusiasts when managed correctly.  All your hard work during the year can now be enjoyed with extended viewing and interaction with your koi. By monitoring water conditions, providing proper nutrition with Hikari® diets, and maintaining an ideal environment, your koi and pond fish will thrive.

For more information on Hikari® products and pond care tips, visit Hikari USA.