is it a real fish? Where are you putting it? Thats interesting, I've never heard of them before.

Yes it is, heres a link to a pic, it kinda looks like a guppie but its not, some shady characters have been known to sell guppies as moquito fish (Gambusia) so beware! you can usually tell the differance from the mouth, the Gambusia has its mouth on the top front of the head, so Ive heard, Im going to put them in the tank? The bottom of my set up is water (about three inches) over gravel, they like temps between the upper 70's and lower 80's, and live in an environment similier to the "betta" somewhat stagnent shallow puddles if you will, perfect breeding ground for mosquitos! dont get me wrong, my waters far from stagnent, as there is no other standing water in my home besides the goldfish tank, I guess the moths didnt have much of a choice but to place there little larvea in my tank! LOL! (cause the gold fish would definitely eat them!)
http://cvmvcd.org/Mosquito%20fish.jpg

Gambusia are evil fish, and you must never ever ever release them dead or alive into the wild. They are Okay at eating mosquitoes, probably about as good as guppies, but they are much better at eating small fish like the fry of native species, they are also hardy down to 40F so they won't be cold killed in a pond or lake. IMO a betta would be a better choice for moth larve control, as bettas are nicer fish in general, and pretty to boot.

Gambusia are evil fish? Dude, have you ever noticed that a majority of fish not only eat their young But also the young of other fish? as for release into the wild? I think that any one that would do such a thing is a total idiot! People have done this with many species of animals in the past (some with very good intentions) with disasterous results! I am not that stupid! (although I do admit to some less than "Albert Einstien" moments!LOL!) also, you state,"They are Okay at eating mosquitoes, probably about as good as guppies," have you ever kept this fish!? I have NEVER seen a guppie eat no where near as much as Gambusia!? They are not just "OK" at eating the larvea, They are little eating machines! =) to try to compare their appetite to guppies is a joke! another statement,"IMO a betta would be a better choice for moth larve control, as bettas are nicer fish in general, and pretty to boot" OK?...the bettas found in the wild are a much better choice than the slow, lanky, slow eating "showfish" people sell at most, if not all, pet shops, they are nice looking fish, but in my opinion thats all they are, one betta wouldnt be able to eat all the larvea in a month let alone a day! not even a wild betta, If I would have gotten a wild betta he would have had a steady supply of food for the rest of his life, thats all, the moths reproduction cycle is way to fast for the slow appetite of a single betta, my Gambusia knocked them out before the end of the day! Yes they are aggresive, as a lot of others are, but that was the kind of fish I needed for the job, not the slow betta? have you ever kept bettas with other bettas? (male or female?) they are among the most aggresive fish Ive ever seen! people dont realize this due to the fact that most have only seen the quite little guy hovering peacfully in his little bowl, yeah put him in with others of his kind, youll see what relentless little killer demons they really are! and the part that kills me is that they dont eat the other fish! they just want to kill them! They do this instinctively due to the fact that in the wild they live mainly in small "puddles" of mostly stagnant water and have to do this in order to survive in an environment that is lacking most everything, food, oxygen, and so on, they need what little they have for themselves, this is also why they are slow eaters and have a very slow batabolism., so yeah, Gambusias got the job done.

I am aware of there appetites, and the implications of size and physiology, I have kept all of these fish and I know how mean bettas are to other bettas and other fish with flowing fins and labrinth orgains(Gambusia will destroy a betta pretty fast too) The reason that Gambusia eat so much faster than guppies is because the Gambusia that you get are mature, the guppies are smaller, you need to get more of them or big females to equal there size but a Gambusia and a guppy of the same size will eat approximately the same ammount, I have seen it in both my freshwater tanks and my Saltwater tanks (I kept them in my reeftank for a few months when I Donated my freshwater tank to a very unhappy turtle) There is allot of hype about how great Gambusia are and how wonderful they are but in fact they aren't that good at dealing with Bugs, in studies when they are released into bodies of water by govt, orgainization to deal with mosquitoes they don't acctually fix the problem, they seem to do nothing except reduce the native fish populations drasticly, now if they go into an empty body of water they will reduce the mosquitoe population, but so will fish that are vastly herbivorous like goldfish.

Your right about the release program, they are kinda hyped up as to the job they will do on the larvea in local ponds and such, but in an enclosed smaller body of water (like my set up) they do a fantastic job =) both the gold fish and the guppies i used died of fungus just a couple of days after I added them, the Gamusia seems to do very well in small bodies of water and hasnt shown any signs of disease. The guppies were nice large females (3) and one male as I thought they would mate (as they always seem to do) but as mentioned they died of the fungus soon after they were introduced to the tank, I had a 110G mini reef and a 100G fresh water set up, they were pretty cool but I got rid of them due to lack of space =(

Goldfish are a bad chice for any small body of water as they are both messy and they grow very large, interestingly enought I have never kept Gambusia without them getting mouth fungus, all four batches that I have bought have developed mouth fungus within weeks of going into my tanks, even in saltwater (a saltwater dip is supposed to help fix Columnaris infections, but a week in full strength salt water did nothing) but none of them died from it, different fish in different tanks (that never shared anythiong except for me) in different states and columnaris in all of them, no clue why, I think its just a massive coincidence. Shame about the Guppies, I must assume that it was just a bad batch, Something you might want to try is a population of endlers, there is a strong founder effect but not the purposeful inbreeding of line breeding programs.