19.1  Common perch (perch) are greenish with red pelvic, anal and caudal fins. They have five to nine dark vertical bars on their sides. They  vary greatly in size between bodies of water. They can live for up to 22 years, and older perch are often much larger than average; the maximum recorded length is 60 cm (24 in). The British record is 2.8 kg (6 lb 2 oz), but they grow larger in mainland Europe than in Britain. 

19.2  The perch is to be found in deep, fresh water lakes and slow moving rivers all over Europe, excluding the Iberian peninsula. They have been found in the Kolyma River in Siberia to the east. It is also common in some of the brackish waters of the Baltic Sea.
The perch has been widely introduced, with reported adverse ecological impact after introduction.

19.3 The  perch is a predatory species.   Juveniles feed on zooplankton, bottom invertebrate fauna and other perch fry while adults feed on both invertebrates and fish, mainly stickle-backs, perch, roach and minnows.

19.4 The perch spawns in the Northern Hemisphere between February and July, depositing its eggs upon water plants, or the branches of trees or shrubs that have become immersed in the water. The eggs have been known to stick to the legs of wading birds and then be transferred to other waters where the birds visit.

19.5  The first scientific description of the perch was made by Peter Artedi in 1730. He defined the basic morphological appearance of this species after studying perch from Swedish lakes. Artedi described its features, counting the fin rays scales and vertebrae of the typical perch.
In 1758, Carl Linnaeus named it Perca fluviatilis. His description was based on Artedi's research.

19.6 The common roach (roach) is a small fish, often reaching no more than about 35 cm; maximum length is 45-50 cm. The body has a bluish silvery colour and becomes white at the belly. The fins are red. The number of scales along the lateral line is 39-48. The dorsal and anal fins have 12-14 rays. Young specimens have a slender build; older specimens acquire a higher and broader body shape. The roach can often be recognized by the big red spot in the iris above and beside the pupil.

19.7  The roach is found throughout Europe, and its distribution reaches eastward into Siberia. 

19.8 The  roach mostly feeds in the deeper parts of lakes, but can be found in any water body deeper than 20 cm (7.9 in) and wider than 1.5 m (4 ft 11 in), and adapts to local circumstances.  In summer however, it can be caught using surface floats and bread. It tolerates organic pollution and is one of the last species to disappear in polluted waters, but is also often the most numerous cyprinid in nutrient-poor waters. It also tolerates brackish water. The lethal temperature is around 31°C (88°F).

19.9 In most places where it is found, it is the most numerous fish, although not in Lake Annecy where it is surpassed by the Perch.  The roach is a shoaling fish and is not very migratory. In the cold season, they migrate to deep waters, where they form large and dense shoals. 

19.10 The roach mostly inhabits waters that are somewhat vegetated, because larval and young fish are protected by the vegetation and the mature fish can use it for food. The common roach eats plant material, bottom-dwelling (benthic) invertebrates, and plankton. Young fish feed mainly on plankton, while the mature fish feed mainly on benthos. They can adapt to environments where invertebrates are scarce by slowing their growth, maintaining slender body shapes, and early maturation.

19.11 The spawning season is in April and May. Most often, spawning occurs on sunny days. Roach generally spawn at the same location each year. Large males form schools where females enter. Males trail the females and fertilize their eggs. The behaviour is rough and the fish often jump out of the water. A female can lay up to 100,000 eggs. When the pH of the water is below 5.5, the roach cannot reproduce successfully.

19.12 Common whitefish,  Coregonus lavaretus, or the lavaret, is considered to be endemic to Lake Annecy, Lake Bourget and Lake Aiguebelette in the Rhône river basin in France, whereas it formerly also occurred in Lake Geneva.  

19.13 It is widespread from central and northwest Europe to Siberia.  Genetic studies suggest that the whitefish diversity within this complex is mostly of post-glacial origin.  

19.14 There is much variation among the European whitefish forms, but in general they have a tapered body, a slightly protruding upper jaw and a fleshy dorsal fin that is typical of the salmon family.

19.15 Whitefish mostly feed on bottom-dwelling invertebrates or zooplankton. Larger fish also take insects off the surface of the water and eat fish fry.

19.16 Breeding takes place in the autumn between September and November, largely depending on the water temperature. Different populations in the same sections of water may spawn at different times. Many populations in seas and lakes tend to make their way up-river to spawn, but others populations remain in lakes or the sea even when breeding.

Northern Pike

19.17 The northern pike gets its common name from its resemblance to the pole-weapon known as the pike (from the Middle English for 'pointed'). 

19.18 Northern pike are most often olive green, shading from yellow to white along the belly. The flank is marked with short, light bar-like spots and a few to many dark spots on the fins. Sometimes, the fins are reddish. 

19.19 Pike take big prey and are not very particular. They are  found in sluggish streams and shallow, weedy places in lakes, as well as in cold, clear, rocky waters. They are typical ambush predators; they lie in wait for prey, holding perfectly still for long periods, and then exhibit remarkable acceleration as they strike. In short, they inhabit any water body that contains fish, but suitable places for spawning are essential for their numbers. Because of their cannibalistic nature, young pike need places where they can take shelter between plants so they are not eaten. 

19.20 Because of cannibalism when food is short, pike suffer a fairly high young mortality rate. Cannibalism is more prevalent in cool summers, as the upcoming pike have slow growth rates in that season and might not be able to reach a size to deter the larger pike. Cannibalism is likely to arise in low growth and low food conditions. Pike do not discriminate siblings well, so cannibalism between siblings is likely.

19.21  Pike have a strong homing behaviour,  they inhabit certain areas by nature. During the summer, they tend to group closer to vegetation than during the winter. 

19.22 Pike are physically capable of breeding at an age of about two years, spawning in spring when the water temperature first reaches about 9 °C (48 °F). They have a tendency to lay a large number of eggs. A likely explanation for such actions are to produce as many surviving offspring as possible, as many most likely die early in life. The young free-swimming pike feed on small invertebrates starting with daphnia, and quickly moving on to bigger prey. When the body length is 4 to 8 cm (1.6 to 3.1 in), they start feeding on small fish.

19.23 The northern pike is a largely solitary predator. It migrates during a spawning season, and it follows prey fish like common roaches to their deeper winter quarters.

19.24 Notably in Britain and Ireland, pike are greatly admired as a sporting fish and they are returned alive to the water to safeguard future sport and maintain the balance of a fishery. 

Arctic Char

19.25 Arctic char or  is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is circumpolar. It breeds in fresh water, and populations can either be landlocked, remaining in fresh water for their entire life cycle, or anadromous, where they return from the ocean to their fresh water birth rivers to breed. No other freshwater fish is found as far north; it is, for instance, the only fish species in Lake Hazen on Ellesmere Island in the Canadian Arctic. It is one of the rarest fish species in Britain, found mainly in deep, cold, glacial lakes, and is at risk from acidification. In other parts of its range, such as the Nordic countries, it is much more common, and is fished extensively.

19.26 The Arctic char is closely related to both salmon and lake trout, and has many characteristics of both. The fish is highly variable in colour, depending on the time of year and the environmental conditions of the lake where it lives. Individual fish can weigh 20 lb (9.1 kg) or more with record-sized fish having been taken by anglers in northern Canada. Generally, whole market-sized fish are between 2 and 5 lb (0.91 and 2.27 kg). The flesh colour can range from a bright red to a pale pink

19.27  Spawning takes place from September to November over rocky shoals in lakes with heavy wave action and in slower gravel-bottom pools in rivers. As with most salmonids, vast differences in coloration and body shape occur between sexually mature males and females. Males develop hooked jaws known as kypes and take on a brilliant red colour. Females remain fairly silver. Most males set up and guard territories and often spawn with several females. The female constructs the nest, or redd. A female anadromous char usually deposits from 3,000 to 5,000 eggs. Char do not die after spawning like Pacific salmon and often spawn several times throughout their lives, typically every second or third year. Young char emerge from the gravel in spring and stay in the river from 5 to 7 months or until they are about 6–8 in (15–20 cm) in length.

19.28 The char diet varies with the seasons. During late spring and summer, they feed on insects found on the water's surface, salmon eggs, snails and other smaller crustaceans found on the lake bottom, and smaller fish up to a third of the char's size. During the autumn and winter months the char feeds on zooplankton and freshwater shrimps that are suspended in the lake and also occasionally feeds on smaller fish.

19.29 The tench  is a fresh- and brackish-water fish of the cyprinid family found throughout Eurasia from Western Europe including the British Isles east into Asia as far as the Ob and Yenisei Rivers. It is also found in Lake Baikal. It normally inhabits slow-moving freshwater habitats, particularly lakes and lowland rivers. It is  most often found in still waters with a clay or muddy substrate and abundant vegetation. This species is rare in clear waters across stony substrate, and is absent altogether from fast-flowing streams. It tolerates water with a low oxygen concentration, being found in waters where even the carp cannot survive.

19.30 Tench have a stocky, carp-like shape and olive-green skin, darker above and almost golden below. The caudal fin is square in shape. The other fins are distinctly rounded in shape. The mouth is rather narrow and provided at each corner with a very small barbel. Maximum size is 70 cm, though most specimens are much smaller. A record fish caught in 2001 in England had a weight of 15 lb 3 oz (6.89 kg). The eyes are small and red-orange in colour.19.30 Tench feed mostly at night with a preference for animals, such as chironomids, on the bottom of eutrophic waters and snails and pea clams in well-vegetated waters. The tench has very small scales, which are deeply imbedded in a thick skin, making it as slippery as an eel. Folklore has it that this slime cured any sick fish that rubbed against it, and from this belief arose the name doctor fish.19.31Breeding takes place in shallow water usually among aquatic plants where the sticky green eggs can be deposited.

19.31 Spawning usually occurs in summer, and as many as 300,000 eggs may be produced. Growth is rapid, and fish may reach a weight of 0.11 kg (0.25 lb) within the first year.

19.32 Tench are edible, working well in recipes that would otherwise call for carp. They are an important target for coarse angling and are used as fodder for predatory species such as bass. Tench, particularly golden tench, are also kept as ornamental fish in ponds and less frequently aquaria.  The best methods and bait to catch tench are float fishing and legering with a swim feeder using maggots, sweetcorn, pellets, bread, and worms. Fish over 1 kg (2 lb) in weight are very strong fighters when caught on a rod.[11]

Common Rudd

19.33 The common rudd Scardinius erythrophthalmus is a bentho-pelagic freshwater fish, widely spread in Europe and middle Asia, around the basins of the North, Baltic, Black, Caspian and Aral seas.

19.34  This species is very similar to the roach (Rutilus rutilus), with which it can be easily confused. It can be identified by the yellow eye colour. The eye of the roach has a big red spot above the pupil, that can be more or less conspicuous.

19.35 The rudd can grow to a size of about 45–50 cm with an average of about 25 cm.

19.36 Rudd prefer clear waters rich in plants. They also feed on aquatic vegetation when the temperature exceeds 18 °C. They hunt for living prey in the upper levels. They prefer mesotrophic waters, while the roach is sometimes found together with the perch in waters that are nutrient poor. Rudd appear to prefer non-acidic water. It prefers shallow weedy areas in lakes and river backwaters, where mature females lay up to 200,000 eggs on submerged vegetation.

19.37 Young Rudd eat zooplankton, aquatic insects, and occasionally other small fish. Mature Rudd, which are about 18” in length and weigh about 3 pounds, eat mostly aquatic vegetation. The Rudd can consume up to 40% of their body weight in vegetation per day, as much as 80% of which is discharged as waste, releasing nutrients into the water column. They can tolerate a wide range of temperatures and water conditions, including eutrophic or polluted waters.

19.38 Maximum lifespan has been reported as 17 years. Sexual maturity has been reported at 2–3 years.

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