I've never seen a Gambusia. They certainly don't occur naturally here. Since everything in the water eats mosquito larvae, I discount that value. Since they occur without stocking, they evidently have some manner of hitchhiking to new water. How do they do that? A pond isn't a Petri dish and I don't want to revisit "the stork brings them".
How do they stack up against Fatheads as far as size? I would assume (dangerous) that they must be faster and more maneuverable that a Fathead to escape predation. A fathead seems to tolerate a wide range of water quality. Do Gambusia also?
It sounds like, to me, that each must have a different niche and different values to the pond owner. They both reproduce heavily. Most small creatures, regardless of environment, do. There appear to be trade offs between the 2. I value fatheads because of their vulnerability to predation and spend about $40 per year on them. Pretty cheap compared to everything else relating to water and I have no idea whether they prey on tiny fry and nests like Gambusia reportedly do. It sounds like the Gambusias main value would be the offering of available fry to feed smaller predators. If a mature Gambusia is smaller and faster than a fathead, their value to anything larger than a very small predators is diminished as far as energy received versus energy expended. However, that is very important, especially to the one inch BG who also needs skinny water.
