In the area where I live, there is a long hot and humid period where we have lots of rain and standing water as a result. Mosquitos can carry disease, they make itchy bumps, and they love to whisper in your ear at night. I have pets that go outside, and there are bugs I dont want to repel, like bees and spiders, so sprays make me feel uneasy, I don't want to hurt something else in the crossfire when all I want to go away are the skeeters.
Mosquitos use standing water to develop the larval stage of their young. Fish love little squiggly things like larvae, and the movement they make triggers this aggression response. I am breeding the fish and selecting for two traits, size of brood, and aggression response. It is not enough that the fish should attempt to eat the larvae, they should kill or maim the rest even when they are not hungry, so this aggression response helps because whether it is digested whole by a fish or in pieces by a cleanup snail is the same result: no whispering in my ear when I'm tending the grill.
I thought it was a fun way to get free food at first, but noted a distinct lack of mosquitos the first year I tried it. The next year I scaled up a little bit, now I took part of the operation indoors during winter to get a jump on the next rainy season.
Poecilla seems to be best for this. The initial assumption was that the big ole dolphin females would be the best eaters, but this seems to only be true when they are imminently pregnant and ready to release fry, they seem to eat or attack anything in sight. Completely by accident, I got a colony of a smaller species, Poecilla Wingei, specifically a flame type variant of the Japanese Blue Endler going in a large enough size to observe their behavior properly. Despite being 1/3 of the size of the other more common Poecilla members (fancy guppy) their speed and aggression response is much higher, as they often kill just for the thrill of it.
Obviously a bunch of dead skeeters will foul the water, so along with a robust bacterial colony and enough botanicals to stave off fungal growth, Ive added cultures of malaysian trumpet snail and pink ramshorn snail. The two are detrivores that eat in alternating shifts so mosquitos that get mangled and touch bottom get eaten and turned into poop fast, which feeds the bacteria, which feeds the plants that export the nitrates out of the water column.
Indicators of a good skeeterfish: upturned mouth, narrow eyes, thicker than normal caudal peduncle, an appropriate gonopodium length for the female they're expected to mate with (some have extremely long gonopodiums that inhibit mating. while aesthetically pleasing, it is an evolutionary dead end), also a behavior that I havent seen written about anywhere, but I call it the zigzag response, which is a sharp increase in activity post water change. The logic behind that is that mosquitos are most active after a rain. a rain brings in fresh water. exacerbated aggression and hunger after the introduction of fresh water typically is a prompt for mating so everyone wants to eat so they can put out the best colors to find the best mate who wants someone who is lively and colorful as possible.
This is a behavior that can be selected for without negatively affecting the colony. I want these things to be pissed off and hungry when it rains. Ive seen this year's skeeterfish snatch a full grown mosquito right off the meniscus without even waiting for it to poop out the eggs, they are that aggressive.
Typically these fish live in estuaries and tributaries, high tide brings in saltwater, and pushes it from the ocean up through the waterways, then rain washes it all back out again. These guys live in either condition, I have them actively tending a high-salinity reef environment right now, keeping algae off the coral and giving the copepods a run for their money. This is a quality known as 'euryhaline', which I guess means they can go from salt to freshwater no problem. What Im trying to say is, wherever you live, you can have these things in a bucket in whatever water, doing work, for free, in a completely symbiotic relationship.
I have suspicions that these ultra hungry and aggressive breeds can stabilize into their own thing and help out with malaria and other mosquito born illnesses. Once I get a stable line of them bred out, Ill start experimenting with shipping them out to other areas. Who knows, maybe African mosquitos taste good too.
Anyway. My wife thinks I am nuts, my friends have no clue. At the end of it all, I got my yard back.