It’s summer, it’s hot, and there’s a great green wave growing over your pond. It’s algae, and as the heat comes, that algae is beginning to go rotten. As algae rots, it uses oxygen to decompose. Unfortunately for the fish and the other animals in the pond, this decomposition process uses the oxygen that pond animals need. In the presence of an algal bloom, the sanctuary of the pond becomes an unpleasant place for these animals to live.
Natural Ways to Control Pond Algae
While there are chemical algae control products, these algae control products often add chemicals to the habitat where your fish, frogs, and other aquatic animals live. If you can, control pond algae naturally. Create a pond that avoids excessive algae growth. Situate your pond in a shady location to avoid the sunshine that helps algae thrive. If you have fish, avoid overfeeding them, since this simply adds fertilizer to the pond and encourages algae to go wild. Add a good quality pond filter that screens the algae in your pond.
Use Pond Fish to Control Algae
Good pond design is important, but sometimes you need some extra help to control the population of algae in the pond. Instead of allowing the algae to control the pond, use your fish to control the algae. Many pond animals eat algae, and in the wild the algae levels in ponds and streams generally stay in check because of these animals. Invertebrates such as mayflies graze on algae, and so do many fish. You can use these animals to your advantage. They need to eat, and you need to control the algae in your pond.
The Best Fish For Algae Control
What fish are the best choice for algae control? Many tropical fish stores sell algae eaters. Many fish are marketed under the name Algae Eater, but often these fish are catfish in the Plecostomus genus. These fish are a good choice for indoor aquariums, but unless you live in a tropical location, they will not live in the pond in the cool fall, winter, and early spring seasons. Snails also eat algae. However, snails sometimes transmit diseases to fish. For this reason, they are best used as algae eaters in a pond that does not have fish.
Instead of buying snails and algae eaters, purchase koi, goldfish and loaches for the pond. Both koi and goldfish graze on algae. The Dojo Loach (Misgurnus anguillicaudatus) is an eel-shaped tropical fish that actually prefers cooler water, thriving in temperatures from the 50s to the 70s. It eats algae and also scavenges for detritus on the bottom of the pond.
Balance Fish Populations for Algae Control
Keeping fish for pond maintenance is a delicate balance. Fish eat and defecate in the pond, and this adds nutrients to the water, causing algae to bloom. However, koi and goldfish also eat the algae. As a general rule, to avoid overcrowding and overfertilizing the pond, you should not have more than an inch of fish per square foot of pond water. This means that a 10 foot pond could have 100 inches of fish or 10 fish that are approximately 10 inches long.
It’s a challenge to manage a small, contained ecosystem. By understanding the animals that naturally keep algae in check, you can create a healthier pond ecosystem.
Tricia Edgar - Tricia Edgar is a gardener, environmental educator, and science writer from the Pacific Northwest.
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