Trout are one of the most desired fish species for fly fishermen. They’re smart, sneaky and hard to catch. They also have a dazzling variety of sub-species and can be tricky to identify, especially throughout the different phases of their lifecycle.
No worries, we’ve got your back. We’ve created a comprehensive guide to understanding the wide variety of beautiful fish that the Trout family encompasses, and what makes each sub-species different.
The first step in understanding trout is to see how it differs from salmon, then we’ll go into all the ways in which different sub-species of trout differ from each other.
For more information on trout species and how they can be caught check out some of the best fly fishing books in our breakdown. We also have guides on fly rods such as the Fenwick Aetos of the Orvis Clearwater.
A brief history of Trout Species
Trout are part of the salmonid family of fish, together with Salmon.
They are closely related to Salmon, share many characteristics, and often it takes a bit of knowledge to differentiate them.
Trout are genetically capable of spawning together to produce offspring, but most of them have remained distinct for centuries. The main reason for this behaviour is their adaptation and breeding techniques. Trout have different spawning times and locations, which make it difficult for the different species to mate. Also, they have different food preferences- large trout feed on other fish while small trout eat insects and other small water animals.
The ability to identify the type of fish caught is an essential skill every angler should have. It can be challenging for stream fishers to identify the different varieties of fish found here. Next, we’ll explore the different types of trout fish species and how they can be identified.
Trout Identification: Trout vs Salmon
Salmon and trout closely resemble each other, especially during the smolt state. During this stage, salmon (called the parr) lose their camouflage bars, and their bodies go through physiological changes to help them survive the shift from freshwater to saltwater. Salmon spend most of their time in the brackish river where most trout stay until their bodies adjust to the high levels of salt in the ocean.
At this stage, colour is not a reliable trout definition characteristic. Regulations are species-specific thus, what is appropriate for one species may not apply for another similar-looking one. Here is a guide to help anglers differentiate trout vs salmon.
There are nine species of Salmon that are native to the stream and rivers that flow to the Pacific Ocean and the North Atlantic. Trout, on the other hand, are found in the Aral Sea, Norway’s Rivers and the tributaries of the White Sea.
Both trout and salmon are found in freshwater and marine ecosystems and are popular among commercial and recreational fishers.
The Size of the Body
Trout have round heads and thick bodies, but salmon have adopted more pointed heads with slender, streamlined shapes. Additionally, salmon are heavier as they can weigh as much as 103 pounds. Trout weighs 2.2-60 pounds and measure 16-55 inches in length.
Mouth and Tail
Salmon have relatively smaller mouths, which barely stretch beyond the point under the eye, while trout have large mouths that extend beyond the line that you can draw beneath the eyes. When it comes to the tail, trout have broader, curved tails while salmon have more slender, forked tails. Also, the tails of trout are more slippery than those of salmon. You can tell this by the ease with which you can pick up a salmon by the tail. A trout will just slip away.
The most obvious difference the two fish species is evident in the head and tail areas.
Both Trout and Salmon have vomerine teeth. These are teeth that are specifically designed to grab on to prey and not let it escape the mouth of the fish. They are oriented inwards and look like little hooks and are arranged centrally on the “head” and laterally on the “shaft”. Salmon have small vomerine teeth arranged in one row on the shaft and very few on the vomerine head – the central line of teeth that extends over the middle of the tongue.
On the trout, the vomerine teeth are well developed both on the shaft and the vomerine head though they are arranged in a zig-zag row on the axis. It is the most notable difference that can help anglers release a fish more quickly if size and creel restrictions apply in the area.
Sea trout usually have a lot of black spots located above and below the lateral lines, but those of salmon are fewer and only located over the lateral lines. If you see a fish with a lot of spots that go beneath the midline towards the belly, it is most probably a trout.
Trout and salmon live in freshwater during the early stages of life and migrate to the sea where they reproduce. Sea trout tend to migrate to the streams during the spawning season and return to the sea after this season. Females produce more than 2,000 eggs during this season.
Salmon, on the other hand, stay in the sea for 1-5 years before they are ready for spawning. Unlike trout, some species of salmon spend their entire lives in lakes and rivers while the migratory species travel up to 900 miles to find suitable breeding areas. Salmon females lay more than 5,000 eggs during this season. Sadly, after the hard work of the spawning season is completed, salmon die.
Degrees of deliciousness
Unlike trout, salmon are rich in vitamin D and Omega-3 fatty acids. Trout contain fewer calories, protein and fat, and have yet to reach the popularity of salmon. As such, salmon are extensively cultivated in aquaculture projects around the world and much more frequently used in different cuisines, from Norway to Japan, from heavily smoked to enjoyed raw.
Trout can live for up to 20 years while salmon usually only survive for up to 13 years.
Types of Trout
In addition to trout pictures, there are numerous other methods that can be helpful to anglers who want to identify the various types of this fish species. Weight, habitat, the presence or absence of spots, coloration, fin size, skin texture and slipperiness, teeth arrangement and many more factors can contribute to easy identification of different species of trout.
In the next segment, we cover the most common species of trout, and everything that makes them unique!
It is also called the speckled trout and is the most beautiful of the trout species. Brook trout images show that they have white leading edges and are backed by the colour black on the lower fins. They also have yellow spots on the back, which extend to form worm-like shapes. On the sides, the colour changes from olive to orange or red with scattered spots that make it almost similar to the red trout. Unlike the red trout, the brook trout measures 9-10 inches in length.
Spawning season for Brook Trout is from September to November. Brook Trout are promiscuous as male and female fish will mate with multiple partners throughout the season. It takes about 100 days for the relatively large eggs to hatch. The sensitive larvae will hide in the gravel until they’ve exhausted all of the nutrients from the yolk sac, and only then will start their adventure.
They are easy to catch, and their numbers reduce drastically due to excessive trout fishing activities or the changes in their environments. Most of them inhabit the northeastern regions of the United States, throughout Canada, western Minnesota and the southern side of the Appalachian mountains of North Carolina.
Brook trout are rare as they found in the remote headwater streams. They prefer wading through the clean, cold mountain streams like the Chesapeake Bay watershed and are most active in the early morning hours and at dusk. Anglers looking to catch brook trout during the day may need to explore the deep waters.
Brook trout feed on the adult and the nymph forms of insects, ants and beetles and small fish when available.
Brown trout vary greatly, depending on their habitat; there is the sea trout, small resident trout and lake brown trout. It is difficult to distinguish between the small resident trout and those preparing to leave their birthplace for the sea. The small resident has developed sexual organs while the fingerlings do not.
Brown trout images show that those living in the sea have a silver colour and dark back. The sides and covers of the gill have lots of black spots and a lateral line above and below. Those living in lakes are also silver, though they have a brownish shade with spots surrounded by paler halos.
When spawning, the brown trout leave the lake or sea and swims up to their native river. They prefer breeding in small streams and rivers. The small resident brown trout spends its entire life in the stream hence, does not need to migrate during the spawning season.
Brown trout feed on small invertebrates that live at the bottom of the sea and plankton while the lake brown species feeds on smelts, whitefish, bleak and other pelagic species. They occasionally move to the river to look for surface insects and larvae.
The brown trout leaves in freshwater found in the sea areas. It demands clean, cold and well-oxygenated water in rivers and large lakes. As such, you are likely to find brown trout in Finland.
According to most rainbow trout pictures, the appearance of the species closely resembles that of the salmon, though its shape and colour vary based on age, habitat and sex. The back takes on different colours based on the time of the year. For example, the reds, yellows, greens and violets appear bolder. The rest of the body has dark spots on the upper part above the lateral lines and on the upper fins while the lower side has a silver colour that fades into a white shade beneath.
Rainbow trout are carnivores, eating aquatic insects and other fish, such as the salamander and crayfish. They also feed on stoneflies, mayflies, nymphs, pupae, algae and small molluscs. This trout is known to cover vast miles upstream to look for food.
Rainbow trout live in the cool waters of the Northern hemisphere but have also been found in the Pacific Ocean, the Pacific Coast of North America and the eastern coast of Asia. They do not thrive well in lakes where most anadromous fish stay.
There are two types of the rainbow fish- the steelhead (partly lives in the river and partly in the sea) and the freshwater rainbow trout.
Rainbow trout mature at the age of 3-5 years, which makes their reproductive organs develop faster than any other kind of trout. They reproduce during early spring or late winter when the temperatures rise. The female adult migrates to shallow streams with clear water to spawn.
This season lasts up to five months (late March to early July) based on the winter conditions and the location where rainbow trout produces 200-8,000 eggs. Hatching may take up to four months, which is based on the
Cutthroat trout have distinctive orange marks on the undersides towards the lower folding of the gill plate area. These unique cuts give them the name cutthroat trout, as the orange line under their throat looks like a cut. Their colours vary from one species to another. However, most of them are recognised by the type of spots on the fish. There are those with yellow spots while others have red ones.
The lake trout inhabits large water bodies as it is the largest of the trout species. It has a green, dark purple or silver colour based on its habitat and its flesh can be white or orange, depending on its diet. Smaller lake trout have a red-orange flesh as a result of the high concentration of insects, flies and crustaceans in their food. Lake trout mainly pursue large prey, including other types of trout, so if you are going for lake trout fishing, carry large lures or bait. Whitefish, ciscoes and the graylings are a great source of food for this wild trout.
These are the smaller species of the trout family. Just as their name suggests, they have a golden colour with red-orange stripes on the side. Also, the rear just before the tail is spotted with dark marks. The golden trout lives in high-altitude freshwater rivers and lakes located in the mountainous regions. They feed on surface insects, small crustaceans like the freshwater shrimp and terrestrial insects. Due to the scarcity of insects during winter, golden trout have a specific feeding season, which begins in May and ends in September. Golden trout also live in freshwater bodies in the western regions of the United States. Specifically, you will find them in Washington, California, Idaho and Wyoming.
This brief guide should help any angler with trout identification during fishing.
Trout pictures should not be the only guides when trying to distinguish the varying species in existence. Their colours, location of spots, adaptations, habitat and other unique features should help you determine the type of trout fish you are dealing with and the fishing techniques to employ.