Species Guide

Rainbow Trout

Scientific Name
Oncorhynchus mykiss
Family
Salmonidae
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SIZE AND WEIGHT

Rainbow trout can grow to over 5kg (11lb) in rivers (depending on the abundance of food sources), but anything over 3-4kg (7-9lb) is considered an excellent fish.

However, the unique environment of the Tekapo canals (in New Zealand) can see them grow to well over 8kg (17lb).

DESCRIPTION AND DIET

DESCRIPTION

A rainbow trout has silver flanks and dark green back covered with black spots. They also have a pink stripe along the flank, beginning on the gill cover and fading as it nears the tail. The colouration varies widely between fish, from a dull pink through to a bright red or orange in spawning fish. Rainbow trout darken in body colour (especially the back) in winter when spawning.


DIET

Rainbow trout are carnivorous, with young fish eating aquatic and terrestrial invertebrates along with worms, molluscs and crustaceans. Adults feed on small forage fish.

SPAWNING

To spawn, trout need a bed of gravel or small stones, with oxygenated sub-surface water filtering up through the rocky bed. These are usually found in mountainous upper reaches of rivers and tributaries.

In suitable natural environments, the female trout digs a deep redd (trough) by lying on her side and flapping her tail to dislodge gravel. She releases eggs, which mix with milt (sperm) from a closely accompanying male and become lodged in the redd. The female then dislodges more gravel to fill in the redd.

After hatching, the larvae, called ‘alevins’, remain in the redd, absorbing the yolk sac. At this stage they look like tadpoles. Within two months, they become young fish (fry) and emerge to feed.

WHERE TO FISH

Rainbow trout love clear, well-oxygenated, cold-water rivers with shingle or rocky bottoms, deep water, and lots of tree cover. They also live in lakes if there is cold, deep water. Their ideal temperature range is between 10° and 16° Celsius.

In New Zealand, you’ll find them throughout the North and South Island’s rivers and lakes, particularly Lake Taupo.

In Australia, they’ll be found from Spring Creek in southern Queensland and in the cooler waters at higher elevation across NSW and Victoria. You’ll also find them Tasmania, in the hills of South Australia and south-western Western Australia. Some sea-run rainbow trout can also be found in Tasmanian estuaries.

WHEN TO FISH

Rainbow trout are not fussy about which time of day they like to be out feeding, however, night time can be a good time to target bigger fish, as they come closer to shore.

Both New Zealand and Australia have restrictions on when and how you can catch rainbow trout. Please ensure you are up to date on the current rules and regulations in the area you are fishing.

In New Zealand, trout seasons are determined by if the water is classified as a spawning water. Most main rivers remain open up to a certain point, but the smaller tributaries are typically closed and vary for time around the country. Some waterways like the Tongariro River in Taupo aren’t closed at all to allow fish to be caught on their spawning run up river, before the river is closed higher up.

HOW TO FISH

Rainbow trout can be caught with a wide variety of tackle including flies, eggs, lures and jigs. The 2 main styles of trout fishing are spinning and fly fishing.

SPINNING

For spinning, we recommend using 8lb (PE 0.4) Hyperglide® 13x Braid as your mainline, attached to 6-10lb fluorocarbon leader (depending on the size of the fish you’re targeting).

Metal lures like Enticers, Rattle Snacks and Spinmax lures are ideal for fast moving water as the current will enhance their movement. Cast the lure across to the other side of the river and slowly retrieve to swing the lure as deep as possible. The closer your lure is to the bottom, the better. Once the lure has made it to the slack water, retrieve it at the same pace all the way back to your rod tip. Often the fish will follow the lure as it swings, before grabbing it in the slack water.

You can also fish with hard body lures like the BMax series which work best in slower waters like lakes and slow flowing rivers, where they can dive down to their maximum depth without being unbalanced by a fast current. A slow uniform retrieve is best as the lure action will do all the work.

Fishing with soft plastic lures like Dartpsin 3.5” lures are ideal for deeper water, especially pools and lakes. After letting the lure fall to the bottom, raise the rod tip every few seconds to get the blade spinning and impart some action to the body. Fish like to hit the lure as it falls after each jerk.

FLY FISHING

A simple six weight fly rod and reel along with a floating line and backing is all you need to get started. You can attach ready-made leaders or make your own using 4 – 8lb Fluorocarbon or Deception Tippet. The simplest way to make up a leader is to measure out three metres of line and tie one uni knot at the end of the fly line and then tie a fly with a second uni knot to the other end.

The most successful way to fish for trout is by using a fly to imitate the most common food trout like to eat, nymphs. Nymphs are the early stage of insects that hatch underwater. Find slack water on a river and often you will run into some trout.

Cast the fly above the fish and let it drift downstream. Using an indicator on the leader will help to tell you when to strike, but it’s not required.

Dry flies (imitating flying insects) can be used in an identical way but instead of sinking they float along the top of the water.

Streamer or wet fly fishing is using a lure to imitate a fish or swimming nymph. It’s the same technique as swinging a spinner through a pool. Fly fishing with a streamer can be much more success, as it can be presented more delicately and in tighter locations. Flies tend to have more natural movement in them too. Retrieving smelt flies is an excellent way to catch fish in lake regions like Rotorua and Taupo (NZ).

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