Gambusia affinis affinis (Mosquito Fish)

About Mosquito Fish

Mosquito fish are helpful in controlling mosquitoes and are a great addition to man-made ponds. These fish can consume over 100 immature mosquitoes (larvae) per day if given the chance. Because mosquito fish are not native to this area, they can only be used in permanent ponds that are not fed or drained by natural waterways, including creeks, streams, and sloughs.

Female

Male

Mosquito fish can overwinter in ponds with a minimum of six inches of water. If the pond tends to freeze solid or dry up, the fish can be collected and kept in an indoor fish tank until the pond returns. When no mosquito larvae are present, the fish will eat other aquatic organisms or they can be fed fish food or crumbled dog biscuit. Mosquito fish give birth to live young, so protect them from being eaten by the adults by providing a submerged pile of rocks or submerged plants.

The first three stages in a mosquito’s lifecycle require a constant source of standing water to mature into flying, biting adults. Mosquito fish feed at the water’s surface where immature mosquitoes (larvae) can be commonly found. The fish effectively control mosquitoes when used in combination with vegetation management such as:

• Thinning out aquatic plants
• Keeping low-hanging plants out of the water
• Removing fallen leaves from the water surface

Frequently Asked Questions

Read more information about mosquito fish.

Obtaining Mosquito Fish

Multnomah County Vector & Nuisance Control has mosquito fish available at no charge from June through July 2009. Please call first (503-988-3464) to check the availability of fish and to make sure that the office is open.

Hours:
Through June 30, 2009 - Monday through Friday, 8am to 3:45pm
Starting July 1, 2009 - Monday through Friday, 8:30am to 3pm or by appointment

Please Note:

• You must be a resident of Multnomah County.
• The fish must be for an enclosed body of water. Does the body of water have any natural, fresh water flowing into or out of it? If the answer is yes, we cannot provide you with fish.
• We will need to know the surface area of the body of water, i.e., 4’ x 6’ pond.
• You will need to bring your own container, such as a plastic food storage container with a lid.
• Once you are here, you will have to fill out a form with your name and address in order for us to give you fish. We will give you a copy of this form as your permit to transport the fish.

DIRECTIONS:

From I-5 North:

Take the Columbia Blvd. exit
Turn right (west) at end of exit (at stoplight)
Vector Control is approximately two miles west of the exit, on the right-hand (north) side of Columbia Blvd.

Reference Points:

• After the stoplight at Chautauqua Street
• After crossing 3 sets of railroad tracks
• Just before the next stoplight at Portsmouth Street
• Watch for a sign on the right (north) for the Waste Water Treatment Plant and another sign for Multnomah County Vector Control. Turn right at the signs and continue straight down the hill. Just before the main gate to the treatment plant, turn left onto the gravel road. Vector Control is at the end of the gravel road.

From East County:

Get onto NE Columbia Blvd. and head west.

Reference points:

• The Oregon Humane Society is at approximately 15th & NE Columbia Blvd.


• NE Columbia Blvd. changes to N Columbia Blvd. at approximately Vancouver Ave.


• Continue approximately two miles west, after the I-5 exit/entrance ramp.


• See Reference Points for I-5 for further directions.