Brought to you by Santiam Valley Ranch, P. O. Box
613, Turner, OR 97392
503-743-2931
Mosquito
Fish -- Gambusia affinis
History:
Mosquito fish are a member of the Poecilidae Family, more commonly known
as minnows.
They were introduced into Oregon from the mid-west (Southern Illinois
south to Alabama and Mexico). It is thought that the mosquito fish enjoy a wider
distribution throughout the world than any other freshwater fish, due to
introductions of this species to control mosquitoes.
Physiology:
Mosquito fish are small, ranging from 1-2.5". They
are grayish-olive above and silvery below; pigmentation changes to match the
environment.
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Mosquito
fish are opportunistic feeders--they eat plant organisms including algae and
phytoplankton (desmids/diatoms) and animal organisms including mosquito larvae,
nematodes, copepods, chironmid larvae and zooplankton.
Their mouth is located on the upper part of the head, thus they are
uniquely adapted for eating mosquito larvae. Most fish have been observed to eat
50 mosquito larvae in 30 minutes. Larger mosquito fish are cannibalistic and
will prey on newborn mosquito fish, as well as other smaller fish. At
temperatures below 41-degress F, mosquito fish move to deeper water or to the
mud-water interface and become inactive. There is poor over-winter survival in
water less than 18” in depth. |
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Mosquito fish have a wide range of temperature tolerance (32.9-degress F to 107.6-degress F) and high salinity tolerance (15 ppt).
Habitat:
Mosquito fish prefer warm, sluggish streams, drainage ditches or standing
water with abundant vegetation. Mosquito larvae can be reduced by 58-95%
in ponds. However, mosquito fish are less effective
in areas with heavy aquatic vegetation where they are unsuccessful in getting to
pockets of larvae.
Reproduction:
Like others in the minnow family, Mosquito fish produce live young
throughout the summer months and thus are quite prolific.
Males are smaller than the females (1.5-2") and have a specialized
anal fin known as a gonopodium. Females
are larger (up to 2.5") and have a small, rounded anal fin.
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Other
Information:
Mosquito fish have earned a reputation as the number one biological control for
use with mosquitoes. Situations where control has proved to be inadequate are
those which are too cold, too plant-infested, too polluted, too extensive or too
temporary for the fish to achieve mosquito controlling densities. Stocking
of Mosquito fish:
Mosquito fish do not adequately distribute themselves when introduced into a
pond. Ideally, fish to be stocked should be divided into 3-4 equally spaced
areas. Sticklebacks (a small fish with spines along the dorsal fin) will prey on young mosquito fish. |
