The easiest fish to use for mosquito management in small ponds and dams are firetail gudgeons.
Blue-eyes are also an excellent way to control mosquito larvae, (wrigglers). Pacific blue-eyes are a small species only growing to about 4cm. Their favourite food is midge and mosquito wrigglers.
This species of blue-eye are native to most creeks and rivers from about Sydney to Far North Queensland. They will breed and establish a balanced population in most garden ponds and farm dams.
Rainbows are another species that love to eat mosquito larvae.
Most streams in Northern Australia have Australian rainbows in them. The southern-most river system to contain rainbows is the Murray-Darling River Basin. Each stream has a unique colour morph. It may be a disaster to stock a pond or farm dam with the wrong colour morph. If they were to escape and breed with the local colour morph, your local colour morph could be lost forever.
The best way to get the right colour morph is to catch your own. It is legal in Queensland for you to catch a small number from your local streams and stock them in your dam. The best way to find your local colour morph is to follow the down-hill fall of the land from your property to the first creek or river. If the spot you find is not suitable for collecting rainbows, check a map of your area and find yourself a site on the same creek or river that you can collect from. Choose a location as close as possible to your property. Some river systems are quite large, and may contain different colour morphs at different points.
They are easiest to catch at night. Just use a 20ltr bucket, with about 10cm of water in the bottom. You need the 20ltr bucket to stop them from jumping out. Add about a level tea spoon of cooking salt, (not table salt) to the water in the bucket. With a good torch, such as a "Dolphin" the rainbows are easy to spot as they drift in the eddies or near the edge of a steep bank. Use a long handled fine net. A 10 or 12 inch aquarium net is ideal. Use some plastic pipe to extend the handle, such as electrical conduit. Just squeeze the loop at the end of the handle until it slides tightly down the pipe.
Don't charge at the fish as the ripples you make or any sound on the creek bed will spook the fish. When approaching a fish, have your net deep in the water. Slowly lift the net up from under the fish and carefully put them in the bucket. Don't handle the fish as this may cause damage to the fishes slime coating resulting in the fish becoming infected with bacteria. The slime, (mucus) is an important part of the fishes natural immune system.
Don't catch too many as this will overload the bucket resulting in loss of oxygen, and dead fish.
They should be released in you dam as soon as possible. Rainbows will quickly establish a self maintaining, stable population in your dam from just a few fish. 20 fish will quickly fill a farm dam, and for a garden pond even less fish are needed to establish a stable population.
It is illegal to sell any of your wild caught rainbows. Even the off-spring can't be sold with out the appropriate authority from the department of Primary Industries and Fisheries. You should also check how many you are permitted to collect.
It is illegal to stock the wrong fish.
In Queensland, (and most Australian states,) unlawful stocking under section 90 of Fisheries Act 1994, can attract fines up to 2000 penalty units each unit is $75. If hatchery operator sells fish knowing that that they were going to be released into a water where they are not permitted, that can be investigated under section 7 of the criminal code.