Fish in the Water Trough

Do Fish Help Keep Horse Water Troughs Clean From Algae?

Thoroughbred horse drinks water on an equipped pasture from a water tank* Image Michael Dehaan.

If your horses are outside, whether, for a couple of hours or all day, it is important to allow them access to freshwater. Though troughs are a great way to give your horses water, they can unfortunately grow algae. As a solution to keep them clean, maybe you’ve wondered: do fish help keep horse water troughs clean from algae?

Some types of fish are great at getting rid of algae, as they use it as a food source. They are an environmentally friendly and safe way to keep water free of algae. With the right environment and the right species, fish can be used to keep horse water troughs clean of algae.

Using Fish to Keep Horse Water Troughs Clean From Algae

By adding certain species of fish to your water troughs, you can help reduce the amount of algae. In addition, the fish will also likely eat any bugs, like mosquitoes, that may lay their larvae in algae infested water. Both algae and mosquitoes can cause dirty water that can potentially be harmful to horses.

Best Types of Fish to Use

When it comes to keeping fish in a water trough, not just any type will do. The fish need to be hardy and capable of surviving different types of weather. Goldfish and rosy reds are two of the most common types of fish used.

Goldfish are known to be tough in nature, as they can grow to be 10-12 inches and live for up to 30 years. They are inexpensive when bought as “feeders” at a pet store.  When using goldfish in troughs, it is recommended to use a trough that is at least 200 gallons, with a maximum of one fish per every 50 gallons. Since goldfish produce ammonia, there should be plenty of water, with plants* and rock substrate. 

*plants should be chosen based on safety for the horses.

Goldfish do well in temperatures between 60-75 degrees Fahrenheit*. When the temperature drops below 45 degrees, the fish could be brought inside. When the temperature rises above 75 degrees, it could be better if the goldfish (trough) should be kept somewhere with shade. 

*With an increase in water circulation and oxygenation they can thrive up to 100oF. 

Rosy reds can be a good alternative to goldfish and can live in small schools together. They are smaller in size, typically ranging 1-2 inches and they live 2-5 years. They could be brought in when the temperature reaches below 45 degrees but can be kept in temperatures up to 85 degrees.

Both rosy reds and goldfish should typically be fed fish food every other day. Rosy reds will need less food than goldfish since they are significantly smaller. If you have lots of algae however, you may not need to feed the fish on a regular basis. 

Maintaining Water Troughs With Fish

When you first get your fish, allow them to sit in their bags for an hour in the troughs. This will allow them to acclimate to their new environment.  

Water troughs should be kept full so the fish have enough water to swim in. Though bleach is a popular cleaner for troughs, it should not be used when there are fish. The fish should do an efficient job of keeping the algae levels low.

Two kinds of algae: 

Green water algae (where the trough goes emerald green and you can’t see through it) won’t be helped by fish in the trough. 

String algae (Algae in clumps or strands you can see through clear water) will be picked down by goldfish and rosy reds. 

Water quality for the fish

If you have trouble keeping the fish alive in the trough you may have to put the trough in a cooler location in the paddock, or you may have to add a circulating / air pump to the trough. Care must be taken to protect the horses from the power or airlines going to the trough. Since the fish will control mosquitoes in the trough it will be worth it. 

Adding Fish to Your Trough

Troughs can be difficult to clean, as they are so heavy. However, it is still important to keep the water fresh and clean so your horses can safely drink it. Adding fish to your troughs just might be the right solution to keeping them clean.


Best Horse Rider 

Guest blogger, Michael Dehaan is founder and editor-in-chief at Best Horse Rider. Based in Oklahoma, Michael has been working with horses all his life, acquiring rich experience and professional insights, which he happily shares with other fellow equestrians. 

Dr Erik Johnson is a Marietta, Georgia Veterinarian with a practice in small animal medicine. He graduated from University of Georgia with his Doctorate in 1991. Dr Johnson is the author of several texts on Koi and Pond Fish Health and Disease as well as numerous articles on dog and cat health topics.