HOW TO OBTAIN MOSQUITOFISH CONTINUED longer periods of time. Unlike chlorine, chloramines do not dissipate from water Facts about tainer unless the air space is equivalent to left standing overnight. To be completely the water space in the container. Large plas- safe, always pre-treat your water before tic containers, those with large surface ar- adding fish to your pond no matter how MOSQUITO FISH eas, are most practical. Keep the containers In California little you add. Chloramine residuals in out of the sun light during transport. treated water should be below 0.1 mg per INTRODUCING FISH TO YOUR POND liter. For more information visit www.sfwater.org. Fish should be introduced into the pond as soon as possible. To avoid shock when intro- DISTRICT OBJECTIVE ducing fish into the pond, it is recom- To provide an effective abatement pro- mended that you equalize the water in your gram primarily directed toward the control bucket of fish. You can achieved this by ei- or prevention of mosquito production. ther adding some pond water to the bucket, Elimination of unsupervised water im- or place the bucket into the pond for a short poundments is an essential step to safe- time to allow the two water temperatures to guard against mosquito problems. equalize. The San Mateo County Mosquito Abatement DISTRICT APPROACH District has an ongoing program of inspec- Under the California Health and Safety tion and stocking of all known ponds in the Code, mosquito abatements are granted District. This service is done at no additional powers to take all necessary and proper cost to the residents. If you have a pond and steps for the elimination and extermina- would like fish , please call the District office tion of mosquitoes. To implement the at 650.344.8592 to set up a delivery. program objectives, district personnel CHLORAMINES make routine inspections of countless Tap water in San Mateo County is treated mosquito sources, such as ditches, chan- with chloramine (and not chlorine). Although nels, lagoons, drain lines, marshes, these chemicals are toxic to fish, shellfish, creeks, lakes, flood control basins, utility vaults, catch basins, and fish ponds. San Mateo County reptiles and amphibians, they do not affect Mosquito Abatement mosquitoes. When mosquito production is found, ap- propriate action is taken to control or 1351 Rollins Road Chloramines are chemicals which contain Burlingame, CA. 94010 eliminate the problem. chlorine and ammonia. Chloramines are considered safer for drinking water than chlorine because they reduce the formation San Mateo County of hazardous by-products and keep the bac- Mosquito Abatement District Tel: 650.344.8592 teria killing disinfectant in the pipelines for 1351 Rollins Road Burlingame, CA. 94010 POND ENVIRONMENT Bird baths or plastic wading pools are seldom Under favorable conditions, mosquito fish, in Cali- suitable as fish ponds. Shallow water does not fornia, will live 2 to 3 years. Occasionally a large provide adequate protection from elevated GAMBUSIA AFFINIS die-off may occur during the winter months when temperatures or predators. In addition, high low temperatures adversely affect the fish. To temperatures enhance algal growth and de- avoid fish mortality, supplementary feeding plete the amount of oxygen that water can The mosquito fish (Gambusia affinis), a should be done with caution. Overfeeding may retain. close relative of the guppy and a member enhance bacterial growth and cause rapid fouling Limited amounts of algae can be beneficial to of the family Poeciliidae, is used exten- of the water, a condition that may be lethal to fish. mosquito fish. An over-abundance of algae, an sively throughout the world by mosquito Also, artificially fed fish make poor mosquito amount that impedes light penetration, should abatement and vector control agencies for predators. Although mosquito fish prefer the shel- be removed. Removal can be achieved by control of mosquito larvae. Mosquito fish ter of rocks, overhanging plants, and banks, they cleaning the pond or using an application of can survive wide temperature variations do not thrive in heavily shaded ponds. Normally, an appropriate algaecide. If an algaecide is that range from below 0º C. to above 35º the fish seek-out a sunny section of a pond and selected, care must be practiced to specifi- C. (32º F. to 97º F.). It has been observed orient themselves to shallow areas with sub- cally follow the directions. An overdose of the that fry (young fish) are more tolerant of merged vegetation, locations often frequented by chemical could be fatal to the fish. temperature variations than mature fish. mosquito larvae and pupae. It is recommended The adaptability and hardiness of the mos- OPTIMUM POND CRITERIA that some aquatic vegetation be provided in quito fish, coupled with its ability to pro- 1. Ponds should have a minimum 6 inch ponds as shelter since mosquito fish are cannibal- water depth duce large numbers of fry during their life- istic on smaller fish. In large ponds, the mosquito 2. Pond edges should have steep sides time, has made the mosquito fish a valu- fish will sometimes avoid the shaded areas even 3. Rocks and aquatic vegetation should be able biological control agent. present though numerous mosquito larvae are present. 4. Provide a circulation pump to enhance REPRODUCTION This may occur if the fish are fed artificially or if water quality there is an abundance of naturally occurring food 5. Pond lining. If new cement, allow several Mature females range from 2 to 2.5 inches weeks to leach-out lime. Rinse the pond in length while the males seldom exceed in other areas of the pond. During the colder several times, and fill with fresh water. 1.5 inches. Gambusia are livebearers months, fish become lethargic and feeding activity After 48 hours, request mosquito fish for (ovoviviparous), better adapted to begin is reduced. Commercial fish food may be used the pond the struggle for existence than fish sparingly as a dietary supplement when mosquito HOW TO OBTAIN MOSQUITOFISH hatched from eggs. Under favorable condi- larvae are not present in the water. The San Mateo County Mosquito Abatement tions, the fry (newly born fish) reach sexual Normally 6 to 10 fish are sufficient to stock an District provides free mosquitofish to the pub- maturity in 6 to 8 weeks. The females, in a average size pond. The high reproductive poten- lic and are normally available from April season, may bear 3 to 4 broods, the first of tial of the mosquito fish will overcome future prob- through October. Call our office at which may number only a few fry. At sex- lems with mosquito larvae. Where large larval 650.344.8592 to schedule a deliv- ual maturity, a female may produce from mosquito populations exist, it may be necessary ery.Transportation of fish can be critical. Glass 60 to 100 fry in a single brood. The repro- to clean the pond or request your local mosquito and metal containers rapidly conduct heat and ductive efficiency of the female declines or vector control agency to treat the pond to de- in some cases may be toxic to the fish being with age, the broods becoming smaller as stroy mosquito larvae with environmentally safe transported. Avoid sealing the selected con- the reproductive period progresses. insecticides prior to planting mosquito fish.