Expanded fish care
Mosquitofish
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Poeciliidae
Genus: Gambusia
Species: Gambusia affinis
Care level-Experienced
Temperament and Behavior-Shy and allusive, I have kept them for a few years now. They will still scatter and hide with the slightest movement, and they spend most of the time at the surface level in the outside tub.
Lifespan- average 1-3 years
Size- males are smaller by about an inch, and females are large, 2-2.5 inches
Diet- Mosquitofish are not picky eaters and have a strong appetite. They readily accept various foods, ranging from flakes, granules, pellets, frozen foods, or live brine shrimp. They are omnivores, and I have seen them nibbling and picking on algae in the tub and Pond Lilies. You can genuinely see them swimming with agile quickness during feeding time. However, nothing will get them going like mosquitoes, and their namesake gives it away. Mosquitofish are also classified as larvivores, meaning they enjoy mosquito larvae and other aquatic insects. They will devour mosquito larvae with such a high efficiency that they use this species for combating this pest, from backyards to scientific research, Malaria control. When choosing to keep them, do not exclusively rely on mosquitos for their diet when caring for them. However, they are great at helping eat mosquito larvae at all stages and start eating larva soon after birth.
Minimum Tank Size- In my opinion, I believe Mosquitofish do better outside in a pond. Either a patio pond with a small group, a 300-gallon tub, or an addition to any Koi or Goldfish pond. It's not impossible to keep them inside an aquarium; however, I think they do best in a pond environment.
pH-7.0-8.0
Water Hardness- Hard Water
Temperature- One of the advantages of keeping Mosquitofish is the wide range of temperatures they can tolerate. I keep these fish outside in a 300-gallon tub all year long, and I recommend keeping them in a large enough water volume, so the tubs do not completely freeze. During winter, the temperature sometimes dips in the negatives; the Mosquitofish will seek cover towards the lower levels of the tub. They hide within the safety of the surviving algae and leaf litter at the bottom along the tub's edges. The temperatures can reach the 100’s in the summertime, and the Mosquitofish continue to do well. In these warm months of the Spring/Summer seasons, the Mosquitofish breed.
Tank-mates- Mosquitofish are a fantastic species to keep and observe, but I do keep them in a species-only tub outside. They seem to cluster together and get along within their group. If I were to put them with another species, it would be fellow pond fish in a large volume of water. They can act aggressively towards small fish and eat their Fry.
Recommended Group Size- Mosquitofish do best in a group. I recommend you get the most prominent group you can, emphasizing having more males in the group if you can choose.
Tank Setup: When setting up an aquarium for keeping Mosquitofish, I have to say I have never set one up for these fish species inside. I have only cared for them outside in a 300-gallon tub. I began with a small group that was wild-caught. Since I keep them outdoors, having algae does help trap extra mosquito lava. During the winter months, they will slow down and hibernate in the lower levels of the tubs; otherwise, they are always at the surface. They almost require a shallow spot to "sunbathe" and rest. You will always see them resting on a sunshade that always falls in during the warmer months and a floating 55-gallon trash can lid. Having 1/4-1/2 inch, of water in a shallow spot for them is necessary.
Males v. Females- I keep mosquito fish outside in an outdoor 300-gallon tub. Telling the difference between adult males and younger juveniles from a top-only view can be difficult due to being similar in coloration, size, and quickness to scatter. Males are significantly smaller than females and will have an elongated gonopodium.
Breeding- When it comes to breeding, males will actively chase the females. If possible, I recommend you keep more males than females 3 or 2 :1 ratio. The adult Mosquitofish, the females, are noticeably more prominent than the males. I cared for them for at least a year before noticing any fry. It was not until I added many hiding places via floating plants, a 2.5-foot floating driftwood piece, and a 55-gallon trash can lid. By no means does it looks good, but the Mosquitofish take great advantage of this trash can lid. They use the underside as a hiding place, and if you move anything that floats in the tub, you will see a cluster of them together underneath. The Mosquitofish utilizes this trashcan lid by resting on the topside, especially on sunny days. Also, after adding these few things, I began seeing females dropping fry in the very shallow spot readily.
Mosquitofish are not the most colorful fish species, and they are often confused and mistaken for Guppies. Mosquito and Guppies Fish share the same taxonomic Poeciliidae Family. Both are ovoviviparous, meaning they give birth to live young that develop inside the female. However, each falls into a different Genus—these livebearing fish with a similar look are vastly different fish with dramatically different personalities. They stay close together shoaling together. I only have kept Mosquitofish outside in a 300-gallon tub all year long. Mosquitofish can easily handle the colder water, whereas Guppies cannot take the same water parameters. Observing the Mosquitofish, I have kept for a few years, they seem to be on the shyer side. The only way to watch them is to stand completely still with little noise, and they will slowly come out of hiding. Mosquitofish are peaceful to watch and delightful addition to a backyard pond. There does not seem to be much aggression when keeping them with only the same species. However, if added with smaller fish or slower swimming fish, you might see nipping and picking behavior. If adding them to a smaller water volume or patio pond, I recommend keeping them by themselves.