Monday, August 14, 2006

Mosquito-Eating Guppies

I haven’t shared this with the internet audience, but Mike and I put in a small pond over the 4th of July weekend. The final product is somewhat raw looking, so I’ve been waiting to share pictures until I have some impressive before and after images. While I’m still not ready to post a picture, I’m ready to talk about a first-time ponder’s experience with mosquitoes.

Our pond is a still pond. There is no elaborate waterfall or cutesy spitter. I chose to construct a calm, meditative pond for two reasons. First, I just didn’t want to mess with the gear required for running water. I didn’t want to run an electrical line. I didn’t want to maintain a pump. I spend enough time clearing the pumps in my fountain and the kitties’ water dish. Second, once I get the hang of this pond thing, I want to put water lilies in. They require full sun and still water.

The idea of a still pond is great. The reality, though, is that it is a mosquito magnet. Our backyard is already so plagued with skeeters that I go through a can of bug spray a week. I was wary of putting fish in a pond with no aeration, but I couldn’t find any Mosquito Dunks at Home Depot, so I plopped an oxygenating plant and two, 99-cent goldfish in the water. They happily consumed bugs and larvae for about a week, until we had a thunderstorm. Whether it was the sudden weather change or a turnover in the water (the algae bloom died at the same time), I’m not sure, but the fish were belly up the next morning. I suspected that might happen. The water was too warm and low in oxygen to support goldfish for long.

While I dithered over the ethics of consigning two more goldfish to death in the murky waters, the mosquitoes took over. Within days, the pool was seething with larvae. A visit to Funke’s finally yielded Mosquito Dunks and I put a quarter of a doughnut in the water. While the Dunks are advertised as safe for animal water troughs, I felt uneasy adding the chemicals to water my cats drink. I needed to find another solution. I decided to try guppies.

To most Americans, guppies are aquarium fish. I thought of them in the same way until I deployed to Thailand, in 2002. Stationed on a Thai Royal Marine base, I found guppies in nearly every body of standing water. They were swimming in the cement water garden troughs that rimmed a number of the headquarters buildings. Their bright bodies were flashing in the scummy water of drainage ponds. They didn’t seem to make a significant dent in the local mosquito population, but they demonstrated an amazing ability to live in warm, stagnant, low-oxygen waters.

Remembering the tropical guppy, I first used them as mosquito control in a shallow water garden I maintained on the balcony of our apartment in Okinawa. It consisted of a 4-gallon, flattened pot filled with water and studded with a small “rock” island, bought pre-planted with ferns. Before I added guppies, I would find numerous wrigglers when I conducted the weekly water changes. After the guppies, none. Sadly, the guppies died when I left the garden outside during a typhoon. We moved shortly thereafter.

Besides their appetite for mosquitoes and tolerance of still water, guppies have another great quality: their reproductive capacity. One male and one female guppy will result in more babies than you'll know what to do with. In my small, Okinawa water garden, I could only support two fish, so I bought only the showy males. My present pond is larger, but, as guppies are dearer in the U.S. than Okinawa, I could only conscience buying two fish again. However, I doubled my money by buying a male and a female. Two weeks later, I had five guppies. The female looks to be pregnant again. (Guppies are viviparous. The gestation period is about 28 days, so my female was gravid when I bought her.) As guppies are tropical fish, I will either have to overwinter the guppies inside or buy a new breeding pair next spring.

So, does it work? Are my guppies keeping mosquitoes at bay? It is hard to tell. I don’t drain the pond, so I can’t examine the water thoroughly. From the surface, I don’t see any mosquito larvae. (I could see them during the brief period between fish.) Now that I have five fish in the habitat, I’ve begun to feed them in the evening. They seem to be hungry, so I assume they’ve cleaned the pond of other edibles. I have no definitive proof, but I believe I’m maintaining a still pond without adding to the general mosquito population.

Next year, I’m ready to add water lilies to the mix.


Blogger Christine said...

Had no idea ponds would require so much upkeep. I'm rethinking the thought of getting one of those.

12:12 PM  
Blogger Carol said...

Good info about guppies! Thanks!

3:38 PM  
Blogger LostRoses said...

I never thought about guppies. And I 'm not really sure what they are, but I buy feeder fish (like tiny goldfish) at the pet store. I figure no matter what happens to them in my pond it's no worse than being intentionally fed to some other creature for breakfast!

They get to be regular-sized after a while if they live long enough (though I'm afraid they often end up as hor d'oeuvres for the raccoons.) For that matter, I've seen garter snakes eat them too. So do they eat mosquitos? I don't really know, I throw dunks in there just in case.

9:47 PM  
Blogger Christine said...

Do frogs eat mosquitos? My mom's pond has a resident frog.

6:46 AM  
Blogger Jim said...

western mosquito fish (Gambusia affinis) and eastern mosquito fish (Gambusia holbrooki) are both native to the USA and eat mosquitos like their name suggest.

I think Jones Fish Farm in Newtown, OH carried them the last time I checked.

9:16 AM  
Blogger Giddy said...

Some pet stores sell tadpoles that will morph into frogs. Both the tadpoles and frogs will eat the mosquito larvae

12:58 PM  
Blogger firefly said...

Thank you for posting this. I've been wanting to do a still pond also (next spring, looks like) and have toads around to prey on nighttime insects.

Everything I read about ponds says "dragonflies will soon materialize to lay eggs in the water and larvae eat mosquitoes!" but I've learned to distrust advice like this.

It's the same kind of thing that led me to feed squirrels because "one of them will soon take over the yard and chase all the others out!"

Sadly, no.

1:22 PM  
Blogger Kasmira said...

I chose guppies over mosquito fish because they are (a) prettier! and (b) available at a pet store very close to my house.

Next year, I want to add tadpoles to the mix. Mike and I tried to find some in the "wild" but we must have been past tadpole season.

4:52 AM  
Anonymous Pam/Digging said...

I use goldfish in my container pond to control mosquito larvae. They definitely keep the pond clean. But I have also lost a number of them over the years. One day they'll be healthy, the next belly up, and I never can figure out why. I do run a bubbler to keep the water from getting too hot on top, since my pond is above ground and it gets very hot here in Austin. Like guppies, goldfish are inexpensive, and they're pretty too. I've never had baby fish though.

Thanks for the info. I look forward to seeing pictures when you're ready.

1:45 PM  
Anonymous Anonymous said...

We just put a small pond in our North Texas back yard. Fall probably wasn't the best time for it, but the liner was upside down under an oak tree for a few weeks, and the grandchildren kept climbing on it, so it seemed better to go ahead and install it before it developed leaks. There's a small fountain, so I think I can get some skeeter eaters to live, but I want plants, too, and I've read they don't like a lot of water motion. I've ordered some duckweed to try first because I read that goldfish will eat it.

10:53 AM  
Anonymous Anonymous said...

Just wanted to add that you may be able to receive free mosquito eatin' fish from your local abatement program. Check the government pages or something. I assume they have such things in other places as well, though your mileage may vary.

4:51 PM  
Anonymous Anonymous said...

Thankyou for your help, not on the mozzie-eating fish, but on that lillies don't grow in moving water-that's why i can't get the damn things to grow!

3:41 AM  
Blogger windarra said...

We have multiple still water ponds with lillies and one with a fountain in our yard here in Bangkok Thailand. All the ponds were full of guppies when we moved into the house. They seem to thrive in the warm still water and there seem to be no mosquitos coming from, or larvae in the ponds. I have wondered how many guppies each pond can support since there seem to be dozens in each pond, but I hope they are somehow self limiting. So far it seems to be working wonderfully. I suppose it is a symbiotic relationship with the guppies waste feeding the lillies, and the lillies keeping the waste to a minimum. Anyway so far so good. I suspect this arrangement may have been going on for years.

7:46 PM  
Blogger vio said...

Nice article. I have the same problem in my pond @ Bangalore. I had a few guppies they went tummy up . Time to add a few more. Got a few molly and they just went into family expansion mode. Don’t think they particularly like Quito larvae though.

7:53 PM  
Blogger vio said...

Our EMC office moved recently. At the earlier location they had a pond that was not maintained.Yet some one had put in a few guppy and they had bred and were allover the place. makes me wonder somehow when u do high tech stuff ,spend money things dont work. Dont care leave it to nature ...and whoa!!

7:59 PM  
Blogger Adi said...

This comment has been removed by a blog administrator.

8:22 AM  
Anonymous Anonymous said...

Interesting article, but keep in mind that Guppies are an exotic species (non-native to the U.S.) and if they manage to end up in a local natural watersource (a creek or lake etc) they do impact the environment. Mosquitofish may not be as pretty, but they may be worth the extra mile...

2:56 AM  

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