Goldfish in Water Troughs for Natural Mosquito Control

Goldfish in Water Troughs for Natural Mosquito Control by Savvy HorsewomanWhen I first heard about using goldfish in water troughs for mosquito control I assumed it was just a novelty.

After all, how could a few tiny fish make a difference?

Well I’m here to tell you THEY DO! And they don’t require any extra care. It almost sounds too easy, doesn’t it?

How Does it Work?

“Female mosquitoes like to lay their eggs (about 100 to 300 at a time) in a dark spot in still water. The eggs then float on the surface of the water for about 48 hours before hatching into larva. The larva will live in the water for about 10 days eating tiny plants and animals. It then changes into a pupa that floats on the surface of the water for about two
days before the adult mosquito emerges.” Source

The goldfish feed on the larva before they get a chance to mature, which can greatly diminish the mosquito population without any chemicals or pesticides.

This also keeps the fish full and happy all summer long; no feeding required! Just remember to top up your water trough regularly (which you probably already do), and remove any debris.

Some of mine have lived over 3 years and do well over the winter. I use a tank heater to keep the water from freezing, but they’ve even survived a few “heater malfunctions” and are surprisingly hardy.

Helpful Tips

Choose smaller fish that can easily reach all corners to the trough. Goldfish are most common but you can also try guppies or killfish.

– If your fish are being eaten by predators try placing some rocks beneath the water to create hiding places. Dark colored goldfish will be better at camouflaging than bright colored ones.

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– Don’t forget to check for other standing water on your property. I like to keep buckets and wheelbarrows overturned when I’m not using them. You can also add goldfish to ponds, fountains and rain barrels.


If fish aren’t your thing try these Mosquito Dunks. They’re organic, pet safe and last for about a month.

P.S. There’s lots of great tips, opinions, and new ideas in the comments section below 🙂

Goldfish in Water Troughs for Natural Mosquito Control by Savvy Horsewoman


  1. Anonymous
    January 30, 2015 / 5:16 pm

    I've always heard about this, and have always wanted to.. But, now this may sound know of stupid, but I worry about the horses drinking/eating the fish. Has this been an issue or anything? I know it shouldn't, considering horses can drink out of creeks and such without getting fish, but I guess I just need the assurance…

  2. Savvy Horsewoman
    February 8, 2015 / 6:38 pm

    Great question! I was worried about this too, until I discovered how skittish goldfish are in a "natural" environment (outdoors vs. aquarium). At any sign of movement they scoot under the rocks. As long as the water level doesn't get too low, I think it would be nearly impossible for my horses to catch a fish 🙂

  3. Anonymous
    February 25, 2015 / 3:21 am

    Tried this with 8 tiny goldfish (less than an inch in length) in 100 gallon troughs and all but one died over the first week. Our temp here in Western WA is in the mid 50's, low 40's at night. Wondering if I should wait until spring or summer to try again. How about feeding the fish or adding rocks for fish to hide? I love this idea!

    • Savvy Horsewoman
      March 17, 2015 / 2:40 pm

      Rocks and places to hide will make it less stressful, but it's hard to say if that will help. Maybe try again in the spring and see how it goes!

    • Anonymous
      May 17, 2016 / 2:06 am

      The reason they died is first because they are over stocked. I recommend 1 goldfish per 40-50 gallons which is 2 goldfish in a 100 gallon tank, this is because they need to grow (a goldfish can grow up to 1 foot long!) and because they produce ammonia which is a waste product (which is harmful to horses). Second, before adding any type of fish you need to cycle the tank for a month or add beneficial bacteria so it can help the fish not get stressed out and die. This is the reason why horses and goldfish don't mix, because they both require different enviroments and care. Many people think goldfish are not important and don't realize that they require as much care as any animal would. If want goldfish I suggest you read dozens and dozens of articles in how to take care of them because I'm sure that the average American does not know the proper care to give to goldfish.

  4. Anonymous
    March 15, 2015 / 12:54 pm

    Don't the goldfish make the water really nasty?? I've had a lot of freshwater aquarium fish, and out of all the species that I've kept, goldfish have unquestionably been the best at turning a tank or bowl absolutely filthy in a matter of hours (i.e., fish poo… tons and tons of fish poo). I've had them in standard uncirculated goldfish bowls and I've had them as part of community aquariums with filters and pumps and dedicated "cleaner" fish like cory cats. Every time I add goldfish to the equation I very quickly end up with water that I can't stand to have in the house, much less that I would offer to my horses to drink. Has anyone who's tried this had a problem with their mosquito control defiling the water trough??

    • Savvy Horsewoman
      March 17, 2015 / 2:35 pm

      I had the same concerns, remembering what it was like to keep a tank of goldfish as a kid. Yuck! The big difference is the quantity of water (100 gallon vs.10 gallon) and having fresh water added frequently (daily vs. weekly). My advice is to start with just a few fish and keep an eye on the water. I like to empty my troughs regularly and give them a good scrubbing, which I'm sure helps.

  5. Anonymous
    March 17, 2015 / 7:55 pm

    Hmmm I'm not sure this would be the best situation for the goldfish. As a horse/animal lover with a few fish tanks myself, I fear for the well-being of the goldfish. Like some people have mentioned goldfish are pretty messy, and waste will build up pretty quick (even in a big stock tank) and unless you take the fish out every few weeks to dump and refill the water, ammonia is going to build up even if you keep adding fresh water, (that would only dilute it a bit). Temperature fluctuations (day/night and seasonal) are not good for the fish, and I can easily see fish cooked alive in the summer, I know our water tubs can get pretty hot in the sun. With proper care goldfish can live for over 30 years, and the original poster says that the most theirs have lived for is 2 years. Goldfish are hardy and can survive in some pretty miserable conditions, but that doesn't mean it's an enjoyable quality of life life for them. I doubt mosquito eggs alone provide adequate nutrition, nevermind in the winter when they're forced to live in frozen water feeding on algae and hay… I don't have experience with goldfish, but I imagine they must need some sort of protein (the rest of my fish do).Basically I don't see this being a very humane form of mosquito control without a lot of extra work in the form of feeding the fish, maintaining water quality, and installing a more powerful heater that keeps the water way above freezing (although this might actually entice the horses to drink more in the winter, which would be good) Although if someone were willing to put in the extra effort to run their stock tank as a giant outdoor fish tank that happens to provide water to horses, it could be a really cool ecosystem experiment/ decoration thing, maybe a cool project for kids or something. I would just be cautious of advertising the idea as 'low/no maintenance' because it's definitely not if you don't want the goldfish to suffer.

    • Savvy Horsewoman
      March 30, 2015 / 4:01 pm

      While fish may live longer in a small, temperature controlled tank with a processed diet, I don't necessarily feel they NEED to. There's plenty for them to eat outdoors (at least in my area) and by the end of summer they're always fat, healthy looking, and at least twice the size of any goldfish I've kept in a tank. I like to think of them as livestock. I meet their basic needs, and they do the job they're born to do; eat bugs! Just use common sense, and of course, if you feel the fish may be suffering then remove them or make some changes (Ie. move the trough into the shade, supplement with some fish food etc.).

    • Anonymous
      May 5, 2015 / 8:56 pm

      The problem is that if the goldfish lived for just 2 years, then something's wrong. One factor could be the 100% water changes made when you clean the trough.

    • Savvy Horsewoman
      May 5, 2015 / 11:17 pm

      I'd never do a 100% water change! I just move the fish to a smaller holding tank along with the water, and then return the fish and water to the clean tank. I also leave some algae on their rocks. Not sure if it's necessary, but I feel better minimizing any change. I agree the conditions weren't perfect, but fish in indoor tanks often die prematurely too. It's a learning process, just like all animal care.

  6. Anonymous
    March 23, 2015 / 11:44 pm

    Check your state laws though. I'm in Maine, it is illegal to keep goldfish outdoors here. Because they happily survive and reproduce in ponds and lakes if they are accidentally dropped there by a predator.

    • Savvy Horsewoman
      March 24, 2015 / 2:23 pm

      Thanks for the info! A knowledgeable pet store should be able to provide some help choosing fish that are appropriate (and legal) for your area.

  7. Kaitlynn Bristow
    April 19, 2015 / 2:53 am

    You could always get mosquitofish. Very cheap little fish and actually are named after what they eat.. mosquito larvae. They also don't grow too large.. the size of guppies..

    • Savvy Horsewoman
      May 5, 2015 / 10:57 pm

      Great tip! I'll have to see if I can find some in my area.

  8. natasha stolys
    May 26, 2015 / 4:17 pm

    what about the bacteria the fish create? is it fully safe for the horses

  9. Rose Barnette
    August 15, 2016 / 6:56 am

    Is it ok to put the fish in a water trough filled with tap water? I've had them for a year and a half in 100 gallon trough with well water, and we have moved to a house on city/county water…

  10. Rose Barnette
    August 15, 2016 / 6:59 am

    Is it ok to put the fish in a water trough filled with tap water? I've had them for a year and a half in 100 gallon trough with well water, and we have moved to a house on city/county water…

  11. bmills
    January 9, 2017 / 2:00 am

    We have been keeping gold fish in our horse troughs for the last 5 years. We agree with the suggestions mentioned by the poster. Our fish are 5 years old. In the winter we bring the fish into the garage till water freezing is no longer an issue. A water heater would do the trick but we live in northern AZ where it is only an issue for about 2 months. We love our animals and are happy to have the fish join our bunch.

  12. Unknown
    March 8, 2017 / 9:34 am

    I don't know about other States but in Maine you're not allowed any fish that aren't indigenous. Because of concerns that they can get into our natural habitat.

  13. Rakzan
    April 16, 2017 / 4:37 am

    I'm glad I don't live in Maine. By the way, I recommend you watch the movie "A Fish Called Wanda".

  14. Rakzan
    April 16, 2017 / 5:01 am

    Does Main allow 'feeder goldfish'? Here in Missouri, you can get them for 10 cents each. They have the capacity to get real big, but they are raised for bait and food for carnivorous fish. The lucky ones get thrown in a stock tank. They work well for me.

  15. Rakzan
    April 16, 2017 / 5:28 am

    THE FISH EAT mosquito larvae that would otherwise mature into biting, bloodsucking, disease transmitting vectors. Effective mosquito control is a health issue. Consider west nile encephalitis for you, your family, your horses, and don't forget heart worms for your dog.

  16. SunnyAli
    September 24, 2017 / 7:20 pm

    Rakzan, you're hilarious. I have the .10/fish gold fish for my rain barrels. The store told me they don't get more than a 2" max!! Now I'm reading your comment and thinking, Oh, no! I have too many in my rain barrels and I may have to expose of a few :fear:!!! Savvy and Rakzan, do you think they've misrepresented the size??? I was using the mosquito dunks and/or sprinkles (and every other organic method under the sun) the biological bits/dunks weren't even preventing two weeks. The fish have made a DRAMATIC mosquito pop difference in my Houston backyard. I can actually go outside and garden with my small kids!! (I admit…. I do not have horses. But these small "feeders" don't seem as messy as the ornamental goldfish. The ammonia is the one thing I'd be considering keeping an eye on. I've had lots of fish.) "mosquito fish" sound promising???

  17. Summer Noctem
    November 8, 2017 / 12:42 am

    I lived at a property with a huge in ground pool. Thousands of gallons. I swear-millions of mosquitos! I went out and bought 50 feeder goldfish in the summer, dumped them in and they lived for well over 2 years breeding and eating and living without any other form of care from me. (Obviously if there was a drought or something I would add water in to the pool.) We never added food. They lived on the mosquitos and algae in the pool. Once we were finally ready to use the pool as a swimming area again the water was drained and the goldfish given to other people for their ponds. Best $5 I ever spent on mosquito control!

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