Loaches of the Valdayka River, Russia

By Alexey Malyshev

In the third and final part I wish to show the most secret fish of the river. Even many local residents, who like to spend their morning on the riverbank with a fishing rod, do not know about their existence. They all live in shallow waters. These species do not migrate anywhere and the living space of each individual is limited to a couple of square meters only.

The Valdayka River, which takes its origin in Lake Uzhin.

The first on our list is a stone loach Barbatula barbatula. The photos below show morphological differences in stone loach coloration collected here in a limited area of the river (less than 50 meters of the channel).

Stone loach Barbatula barbatula in the Valdayka River.

If you don’t know this is the same species, you can call them all different. In shallow waters, loaches can be observed from late April to late October. In the wintertime they swim to deeper parts of the river. Stone loaches live over sandy-pebble soil with an abundance of medium-sized stones.

Another colour variant of stone loach Barbatula barbatula in the Valdayka River.

Barbatula barbatula are night active fishes. At nighttime they leave their shelter and search for the food in the surroundings – about 10-15 meters away – but once stone loach are full, they always return under their stone.

More colour variants of stone loach Barbatula barbatula.

They feed on bottom invertebrates: crustaceans, worms and insect larvae. The favorite food are small (no more than 2-3 mm) bivalve mollusks – fingernail clams of the genus Pisidium.

fingernail clams of the genus Pisidium.

Stone loaches spawn in early May. Their preferred spawning grounds in the river are calm backwaters with last year’s rotting vegetation. They accumulate in such places in hundreds. Predators like burbots and pikes also come here to feast on spawning fishes. By the end of July the grown-up fry can be easily observed at night in the shallow waters. Photo below is one of such locations, where you can notice the ratio in size between stone loaches and a six-centimeter long minnows.

The spawning grounds are calm river backwaters.

Another secretive inhabitant is the freshwater sculpin of the genus Cottus. In all likelihood, the river is inhabited by two species that differ from each other by morphological features and live in different biotope zones.

Cottus gobio, in the Valdayka River.

The first is the common sculpin Cottus gobio with a more elongated body due to its elongated caudal peduncle, with a wider head and an incomplete lateral line. This species is found only in the rocky or sandy-rocky (with a predominance of stones) zones with no vegetation.

They prefer to hide under large stones and slabs. Sometimes several individuals live under one large stone.

Cottus gobio – this species is found only in the rocky or sandy-rocky.

The second species is apparently Cottus koshewnikowi with a shorter body, narrow and short snout, and a full lateral line. This fish is smaller in size than its counterpart – no more than 8 cm TL.

Cottus koshewnikowi, in the Valdayka River.

This species lives on sandy-rocky or silty-sandy soils. It can be found in the areas with stagnant water or with a very weak flow. Cottus koshewnikowi does not necessarily hide under the stones during the day. It can also choose the vegetation thickets as a shelter.

Cottus koshewnikowi, in the Valdayka River.

In case of danger – this was a real surprise to me – it can partially bury itself in the ground. Both species have similar lifestyles: both are night active and keep staying near their stone.

Cottus koshewnikowi can partially bury itself.

They feed on various aquatic invertebrates – worms, crustaceans, insects and their larvae. Sculpin spawn in late April – early May. One male can spawn with several females. The fish eggs are laid on the bottom side of a flat stone.The photo shows two fish egg cakes on a rock, which means the male spawned with two females. The male guards the clutch, fanning it with its pectoral fins. As soon as the fry swim away, the protective functions of the male are ended.

Cottus koshewnikowi’s fish eggs.

At first, babies hide in vegetation by hang on the stems, but once having reached a size of 1 cm they start an active nightlife. On the photo below there is fry of 2 cm long.

Cottus koshewnikowi’s fry.

Another secretive and night active inhabitant of the Valdayka River is Cobitis sp. (photo 16-18). I defined it as a species for a good reason. According to the established distribution areas this region should be that of Cobitis taenia. But in our Cobitis there are two oblong spots clearly visible at the base of the caudal fin, instead of one in the upper part.

Cobitis sp., in the Valdayka River.

It can be assumed that this is the Siberian spined loach Cobitis melanoleuca, but the closest distribution area, where this fish was officially recorded is 600 km south of the Volga River basin. Cobitis melanoleuca has never been found in the water bodies of the Baltic Sea basin. So probably this one is an undescribed species.

Cobitis sp., in the Valdayka River.

Spined loach preferres to stay over sandy-silty soils. It can be found both in open areas and in the thickets of vegetation. Young one-year-old spined loaches live near the riverbanks in a depth of only a few centimeters. They are night active fishes, which feed mostly on small benthic invertebrates.

Cobitis sp., in the biotope aquarium.

Spawning begins at the end of May on the stones. The main condition is the growth of filamentous algae on their surface, to the algae the female attaches her eggs. At the end of summer one can observe juveniles 2-3 cm long with a translucent bod.

Cobitis sp., juvenile.

Spined loaches hibernate in the same places where it live and breed. Juveniles burrow into the ground. Adults swim to the fast-flowing areas and crawl under rocks.

There is another interesting inhabitant that occurs in the Valdayka River. This is a European brook lamprey Lampetra planeri, which can be seen at most one month in a year, from mid-April to mid-May. The adult lamprey does not feed and its life span is very short – 2 weeks before spawning and 2 weeks after.

Adult Lampetra planeri, in the Valdayka River.

By the end of April males, by using their sucker, build nests on pebble soils in the form of a small hole, where several females lay eggs. Two weeks later blind serpentine larvae appear, which are washed downstream to quieter places, where they burrow into silty-sandy soils.

Detail photo of Lampetra planeri, in the Valdayka River.

This way they live for following 5-6 years. Lampetra planeri feed on detritus and plant fragments. In the last year of the life cycle, in the fall, begins their transformation into an adult lamprey. The photo below shows this process: no longer a larva, but not yet an adult specimen. Here are visible almost formed eyes, but the sucker is not yet developed. The transformation lasts all winter and only by mid-April the process completes. After spawning adult lampreys lurk under stones and die in 2-3 weeks.

Semiadult Lampetra planeri, in the Valdayka River.

For these fish is suitable a low (25-30 cm) aquarium with a large bottom area. Fine and coarse sand is alternately poured at the bottom, some small pebbles are added and flat stones are laid on top. From technical equipment you would need a pump and good filtration.

Fish gradually adapted to captivity will perfectly tolerate temperatures up to 25 – 27 C. Interestingly sculpin in an aquarium is fundamentally changing the way of life. The nocturnal lifestyle get changed to day active life and the fish crowd most of the time near the front glass in anticipation of feeding

Sculpins in the biotope tank.

Sculpins are voracious and need to be fed daily. Barbatula barbatula (below) eventually gets used to captivity and can be seen also during the day. It is better to keep them in a group of 5 or more individuals. Their mates can be small cyprinid fishes – bleaks, minnows, schneiders from the same reservoir.

Barbatula barbatula can be seen also during the day.

Important: for quick adaptation it is better to take soil and decorations (stones, driftwood) from the original habitat. It is suggested not to keep spined loaches together with the stone loaches, as they are more timid and take longer to get full. It is better to feed them immediately after turning off the light, separately from other fish.

Bivalve mollusks in the Valdaika River.

Interesting gastropods in the Valdaika River.

Of course, the fish inhabitants of the Valdayka River are not limited to the listed species. Asp Aspius, aspius, sabrefish Pelecus cultratus, vimba Vimba vimba, which inhabit the river mouth, have not yet been investigated. Brook trout Salmo trutta, which lives in small tributaries with a fast flow on rocky ground, has not yet been documented here.

Interesting gastropods in the Valdaika River.

Also catfish Silurus glanis have not been registered yet. In the past European eel Anguilla anguilla rose up the river from the Baltic Sea, until in the upper reaches of the river a dam was built. Every year the river brings new surprises. My research continues further.