Rainbow trout are the fish that make a lake or a pocket of current feel busy. They will rise, chase and come up through the water in a way brown trout often will not. That does not make them easy. It makes the first honest cast more important than a box full of patterns: find the feeding depth, then put something the right size on that line. The Snowy Mountains lakes are the rainbow fishery in this guide, and the Rainbow Trout in the Snowy Mountains page carries the local detail.

An introduced cold-water fish, now established through the cooler south-east and in the south-west of Western Australia. Lakes, reservoirs and high streams all hold them where summer water stays cool enough. Many of the better-known fisheries are stocking-supported, the Snowy Mountains storages and the tableland trout dams among them, and the water pages draw the stocking record where there is one. Some streams recruit on their own: the Eucumbene and the Mitta Mitta carry wild rainbows in their survey records, and the Blue Mountains gorges hold rainbows that have grown in Sydney’s drinking-water storage and run back up the Coxs in winter.

A recorded occurrence is not a promise that the water in front of you is fishing. Follow the regional guides for the practical picture; lakes and rivers in the same district can fish like different species.

Look for cool, well-oxygenated water with a food supply. In a river that is often the seam beside faster current, the tail of a pool, and the pocket behind a rock. In a lake it is wind lanes, drop-offs, creek mouths and the depth band the fish have settled in that day.

Rainbows feed up as well as across. A nymph or small streamer worked with a lift, or a dry on a warm-evening rise, will catch fish that a dead drift along the bottom never sees. When nothing is showing, start deeper than you think and shorten the drop until you start bumping fish.

Insects, crustaceans and small fish are all on the menu: mayflies, midges and damsels on the lakes in the evening, caddis in the river riffles, mudeyes and yabbies in the storages. Match the depth before you match the hatch.

Rainbows use the open water. They can cruise well out from a lake shore when food is present, moving purposefully and fast, generally upwind, while a brown feeding the same way is more casual and prone to wander. A cruising rainbow in open water looks blue-grey and moves quickly, so you need to see it from long range to have a cast; and when it comes, it gives almost no time to think, unlike a brown that will often give a second chance. At dusk they leave the deep weed beds and cruise the surface whether or not there is a hatch, which is the hour for a conspicuous attractor. Fishing feeder-stream mouths from a high bank, spotting the cruisers first, works right through winter.

In a mainland river the rainbow is a riffle fish more than a run fish. Half-submerged boulders are the feeding hotspot because the insects graze the algae on them and climb them to emerge, and a river of stable boulder structure holds far more trout than one of tumbling small rock or sand. A fish holding in fast water is feeding and will move confidently to a fly; the same fish in slow clear water is a harder proposition. A juvenile dispersing through a system at a few ounces can be a pound by the following summer.

On technique, a hot-spot or bright tungsten bead can help in fast water; in cold water, when a fish is holding in the slow water and spending nothing, a bigger more visible fly fished to provoke beats an imitation. After a refusal on a dry, go smaller and change the colour and profile rather than repeat the cast; if the first fly is not accepted it is often worth simply changing it. Euro nymphing, with the fly line off the water and a coloured leader watched for the take, cycles drifts far faster than an indicator and cuts drag in pocket water, and a little slack in the leader reads takes better than a tight line. Get a hooked rainbow onto the reel quickly and let the drag protect the tippet; a fibreglass rod’s flex saves fish lost to the jumps and head-shakes. When it is time to net one in fast water, get downstream of it and let the current bring it in.

Colour is a poor test. A silvery lake rainbow and a pale stream brown can look closer than the names suggest. Use several marks together.

A rainbow trout typically shows many small black spots across the body and a heavily spotted tail, often with a pink, red or orange band along the side. A brown trout usually carries larger dark and red flank spots with pale halos, and few or no spots on the tail.

If you are not sure, treat the fish as the more protected lookalike until you are. The two are both legal trout in most of the waters this guide covers, but bag, size and season still depend on the jurisdiction and the water; check the current rules before you keep one.

A four or five weight covers most streams; a five or six weight is kinder on a windy lake. Start with a floating line and a nine-foot leader, carry an intermediate for the drop-offs, and carry enough extra tippet to change diameter without rebuilding the whole rig.

The first fly should answer the water, not the box. A visible rise calls for a dry in the size of the food, and a parachute Adams is a sound starting pattern; NSW DPIRD’s Snowy Mountains guide rates it in fourteen to sixteen for the warm-weather evening hatches. A quiet run or the water under a riffle calls for a lightly weighted Pheasant Tail or similar nymph, on a dry-dropper when the fish might look up. A lake edge, a drop-off or last light deserves a Woolly Bugger, which the same guide rates in eight to twelve as a strong low-light choice for rainbows on the lakes.

Rainbows run to spawn a few months after the browns, following the same upstream pattern and dropping back through spring and summer.

Rainbow trout spawn in the colder part of the year, later than browns in many Australian waters, on gravel in tributaries and lake inlets, and in the Snowy Mountains that means lake fish pushing up the feeder creeks in the spring melt as the season opens. Timing is local. Treat fish gathered on shallow gravel as fish to leave alone, and check the current jurisdiction rules for any seasonal closure before you fish a spawning stream.