put your tank outside, without a top/hood. you’ll get all sorts of critters, bugs, worms, etc living in there.

You can culture your own mosquito larvae quite easily actualy, along with many other nutritious live foods. Here is a fantastic article about this written by a knowledgable source.

basicly get a 15 or so gallon buket, fill it with water and leave it outside. in a couple of weeks it will be teaming with the nasty bugers.

the larva will be big enough for your goldfish to eat.

also buy a fine mesh net to catch them with . dont put water from the buket into the tank or pond. bat idea.

but it woud be qucker to and less harmful to the fish to just buy some frosen or freeze dried bloodwoorms from a loal pet store, wich would be esyer for the fish to eat than ghost shrimp.

there are plenty of mosquitoes in nyc, just catch the ones that bite you (mosquitoes that bite are females that need the blood for their eggs) put them in a jar with some water and some dry places for it to land on

they should lay eggs and eventually hatch

You don’t want to use wild mosquito larve…so much bacteria and germs, it would almost definately get your fish sick

I would reccomend some small shrimp…or ghost shrimp….most petstores sell them, and your goldfish could eat those