Mosquitoes in my water tank

Got 4,500 gal of water storage set up on the cheap...free above ground swimming pool from craigslist. I had big plans to cover it before mosquitoes moved in but life got busy and now it's heavily infested with larvae  (as expected) so I dumped a bunch of feeder goldfish in there but they haven't even made a dent in the insane amount of larvae in there. I can't drain it and refill it because the seasonal spring dried up a few days ago and likely won't run again til next year unless we're lucky.  I need to be able to use this water for my ducks so bleach or large amounts of vinegar are not an option and I don't know if the commercial mosquito killer is safe for them so I'm thinking of dumping an edible cheap oil in there to make a barrier floating on the surface to keep them from hatching and more breeding. Is this a viable option? Any other ideas?

There's a product called Mosquito Dunks, it looks like a little bagel. It is Bacillus thuringiensis which is a bacteria that predates mosquito larvae. I don't think you're supposed to use it for human drinking water but I have seen people use it for livestock drinking water and I have used it with great success in irrigation water. It's pretty cheap and pretty effective but in your situation you need to get it in ASAP

I'd stay on course with the fish. That should be all that is needed.

Anyone want to lend Jenn a couple of tilapia?  They'd made quick work of those mosquitoes and then later, fish tacos.  

I've used fish in my farm animal water tanks for years. Works extremely well. Get more fish, then remove excess fish when problem is under control. ~~Not a good idea to pollute your tank with oil or (even benign) chemicals.

Wouldn't benign chemicals, by definition, be harmless?

Bt is harmless to humans. Its a bacterium. I'd roll with it.

I'd stick with the fish, but give them time. We had a similar mosquito population explosion when our pond was set up. We introduced a dozen small goldfish and a couple of weeks later there were no mosquitos to be seen.

I bought the mosquito dunks. Everything I could find said it's safe for the ducks and it's certainly much cleaner than an oil slick. I'll continue with the fish but I just really didn't want a few thousand mosquitos hatching before the fish can catch up, should have just put fish in there the first day.  We'll see if the dunks work as good as they say.

Generally the Bt will wane, and the fish will catch up a little as the mosquito population climbs. Eventually you should get an equilibrium and not need the Bt. Hopefully it saves you abunch of bites.

Checked on the progress about 95% of the larva are dead so far maybe now the fish have a chance.