Lin is a warm-loving, slow-growing, sedentary, typically bottom-dwelling fish. Its structure somewhat resembles that of a chub, but it can be easily distinguished from all carp species by its thick, clumsy body, very thick tail section, very small scales, and very small, bright red eyes. Additionally, lin has an odd number of pharyngeal teeth arranged in a single row, elongated into small hooks on the inside; its mouth is very small, fleshy, and even appears somewhat swollen, with one very small whisker at each corner, and its body is densely covered with slime.
The color of lin greatly depends on the water in which it lives. Generally, its back is dark green, its sides are olive green with a golden sheen, and its belly is grayish; in rivers and clean lakes, it is always much yellower than in shady ponds overgrown with aquatic plants, where lin can be almost completely black. Its fins are very dark.
Lin prefers calm, grassy waters; it avoids fast and cold water and thus is found more in river bays, shallow lakes, channels, and ponds overgrown with reeds and bulrush. However, it does not fear slightly brackish water.
In small stagnant ponds, lin is quite rare because they require relatively clean, albeit warm water for spawning; their preferred habitats are quiet backwaters of rivers, flowing, muddy, and reed-filled lakes, and similar ponds.
Overall, this is a very sluggish and lazy fish. Lin is extremely slow in its movements, mostly lives in the same spot in a river or pond, and only appears in other places during low water. It cannot cope with fast water, and during spring or autumn floods, it is often carried away by the current to distant locations. In such river bays, backwaters, shallow areas, or at the top of a pond, densely overgrown with reeds, bulrush, and especially pea plants, lin spends most of the day digging in the sticky mud and extracting worms—its main food; however, it also feeds on the mud itself and various aquatic plants.
Only in the evenings, mornings, and at night does lin venture out to cleaner areas of the pond, but even then, it rarely surfaces unless it decides to grab a large fly that has fallen into the water.
As a sedentary fish, lin is rarely found in large numbers in one place; except during the spawning period, and even then not always, and in winter, it mostly leads a solitary life and swims alone. In October, and less frequently in early November, lin gather in more or less significant schools and settle for winter in the deepest parts of the lake or bay. Sometimes they completely bury themselves in the mud and, when extracted from there, show no signs of life for a long time.
During spawning, even where lin are quite numerous, they do not gather in dense schools. This is due to the fact that their spawning lasts quite a long time, sometimes two to three weeks. Usually, smaller ones spawn earlier, and larger ones later, which is why one can encounter both young lin and fresh green eggs of this fish at the same time.
There are many reasons to believe that lin spawn in two periods.
The number of eggs in lin is quite significant: Bloch counted almost 300,000 eggs in a 1.6-kilogram egg sac. According to other observations (Erenkreitz), a female weighing 1 kg contains 350,000 eggs.
Lin eggs develop extraordinarily quickly, faster than any other fish—sometimes in three days, but always in less than a week. According to observations by Western European fishermen, a temperature of 22°—24° Celsius is required for egg development. Young lin, distinguished from other fry by their golden color, disperse and mostly swim alone or in small schools in dense thickets of aquatic plants, closer to the bottom; they are rarely caught and almost never venture into clean areas and reeds, similar to young crucians.
Young lin grow quite quickly, significantly faster than crucians, even chubs, and in some feeding lakes and ponds, they reach a weight of 400 grams in two to three years. They become capable of reproduction in their 3rd or even 4th year. According to my observations, lin in feeding ponds reach a weight of 200 grams in one year, 400 grams in two years, and up to 800 grams or more in three years.
In the water bodies of Kyrgyzstan, lin was artificially bred first in the basin of the Chu River and then released into Lake Issyk-Kul, where it established itself in the Tyup Bay and received the status of a "commercial" species.
In water bodies, this fish adheres to dense thickets of aquatic vegetation, where it finds food and conditions for spawning. Like many carp species, it is well caught on a fishing rod in summer.
