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Stone loach

Barbatula barbatula

Photo: Stone loach
Weights and measures
Length from 10 to 18 cm
Biological data
Lifespan 8 r
State of endangerment
Animal description
The Stone loach (Barbatula barbatula) is a small, fascinating freshwater fish native to Europe and parts of Asia. This species thrives in a variety of water bodies, including streams, rivers, and lakes, particularly favoring areas with a soft substrate of mud or sand that it can burrow into. The Stone loach is well adapted to life at the bottom of these water bodies, showcasing several unique features that enable it to navigate and survive in its specific niche.

One of the most distinctive physical characteristics of the Stone loach is its elongated, somewhat cylindrical body, which can grow up to 25 centimeters in length, though most specimens are much smaller. This body shape, combined with a mottled brown and green coloration, provides excellent camouflage against the riverbed, protecting it from predators. The fish's skin is smooth and scaleless, which, along with a layer of mucus, helps it to slip easily through the water and into tight spaces between stones and plants.

The Stone loach has a unique barbel arrangement around its mouth, with six tactile barbels that it uses to search for food along the muddy or sandy bottoms of its habitat. These barbels are highly sensitive and help the fish detect the presence of prey, which primarily consists of small invertebrates such as insect larvae, worms, and crustaceans. This sensory adaptation is crucial for feeding, especially in murky waters where visibility is low.

Another interesting feature of the Stone loach is its ability to breathe atmospheric air. This fish possesses a modified intestine that functions similarly to a lung, allowing it to survive in oxygen-poor environments. During periods of drought or when oxygen levels in the water drop, the Stone loach can gulp air from the surface to supplement its oxygen intake, enabling it to inhabit waters that would be uninhabitable for many other fish species.

The behavior of the Stone loach is as intriguing as its physical attributes. This species is known for its nocturnal activity patterns, spending the daylight hours hidden under stones or buried in the substrate. At night, it becomes more active, emerging to forage for food. The Stone loach is also renowned for its ability to produce sounds, a rare trait among fish. By grinding its pharyngeal teeth or snapping its swim bladder, it can generate clicking noises, which are thought to play a role in social interactions, although the exact purpose of these sounds is still a subject of research.

Reproduction in Stone loaches occurs during the spring and early summer. Females lay adhesive eggs among vegetation or under stones, where they are fertilized by the male. The eggs hatch after a few weeks, and the young fish are left to fend for themselves. Stone loaches can live for several years, with some individuals reaching ages of up to 8 years in the wild.

In summary, the Stone loach is a small but remarkably adapted fish, capable of thriving in a variety of freshwater environments. Its physical and behavioral adaptations, such as the tactile barbels, ability to breathe atmospheric air, and nocturnal lifestyle, make it a fascinating subject of study and a vital component of the aquatic ecosystems it inhabits.
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