Fish - Angling Club of Tolmin

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Marble Trout - Salmo trutta marmoratus

Marble trout

The marble trout used to be the sole species of trout settling our waters. It is an endemic fish of the Adriatic river system. Based on its outer appearance – the phenotype of the trout – as well as its genetic signature, we can tell apart two types of marble trout. Trout of the Zadlaščica type have distinguishing marbled bodies with red coloration being quite rare. Trout of the Idrijca type have red coloration in the form of dots and splotches, usually along the flanks, besides the distinguishing marbled pattern.

Marble trout

The marble trout inhabits all the waters of our fishing sector.

Smaller marble trout feed mainly on bottom-dwelling organisms and aquatic insects while larger ones mostly eat other fish.

Marble trout spawn from the end of October to the beginning of January.

Marble trout in our waters reach quite sizes and weights. The largest marble trout found measured 121cm in length and weighed 25kg.

Grayling - Thymallus thymallus

Besides the marble trout the grayling is the only autochthonous salmonid species of fish in our waters. A Soča grayling is said to exist, which varies from the grayling in the Sava in that it has a grayer body color and no black dots in the front.

Grayling

It inhabits the Soča from the Soča gorges down river, the Koritnica from Kluze onwards, the lower reaches of Učja, Bela and Nadiža, the Tolminka from the dam in Tolmin, the Idrijca, Trebuščica from the Jelenka down and Bača from Koritnica onwards. Individual grayling can also be found in the Kneža. It is rarely found in river feeding streams.

It feeds on bottom-dwelling organisms and aquatic insects, as well as occasionally with the young of other fish.

It spawns from mid-March to the beginning of May.

In our waters it reaches sizes of up to 60cm and weights of up to 2kg.

Brown Trout – Salmo trutta fario

Brown trout

This is not an autochthonous trout of our waters. It was first brought here at the beginning of the 20^th century. It successfully crossbreeds with the marble trout and their offspring are fertile. This is the reason why the brown trout is such a threat to the marble trout and why it has become illegal to introduce it into waters of the Adriatic river system in Slovenia.

Except for five locations with pure marble trout, the brown trout is found in all waters of the sector.

Smaller fish feed mainly on bottom-dwelling organisms and aquatic insects while larger ones mostly eat other fish.

In our waters it spawns from the middle of December to the end of January. The lake form of the brown trout spawns from the end of October to the beginning of December.

In our waters it reaches up to 70cm and 6kg.

Crossbreeds between the marble and brown trout

Hybride

Crossbreeds vary greatly in appearance. They can be very similar to marble trout, have mixed features or be nearly indistinguishable from brown trout.

Distinguishing between crossbreeds and both subspecies, especially the marble trout, is very difficult with crossbreeds which can resemble them greatly. Careful inspection of the trout is required to tell them apart, especially the gill lids, where differences are usually most noticeable.

Hybride

Crossbreeds can be found anywhere where populations of both marble and brown trout are present.

As other trout, crossbreeds feed on bottom-dwelling organisms, aquatic insects and other fish in the case of the larger ones.

They spawn from the end of October to the end of January.

Crossbreeds grow to 1m long and 10kg in weight, however they do not reach the exceptional sizes of the marble trout.

Rainbow Trout – Oncorhynchus mykiss

The rainbow trout entered our rivers from fish farms, especially to make fishing more interesting. When it was first introduced into the rivers it didn’t breed, but it quickly adapted to local conditions and began to breed and has thus come to inhabit waters where it wasn’t originally introduced. It doesn not crossbreed with the marble trout, however it is an aggressive competitor for food and space and a very dangerous competitor in the spawning grounds, where it appears after the marble trout.

Rainbow trout

The rainbow trout can be found in the Soča from Vrsnik, in the Koritnica from Kluze on, in the lower reaches of Učja, Nadiža and Bela, in the Tolminka from the dam in Tolmin, in the Idrijca, in the Trebuščica from the Jelenk, in the Bača from Klavže down. Individual fish can be found in the upper reaches of the Tolminka and Bača rivers.

It is not selective as far as feeding is concerned and eats any available food.

In our waters it spawns from December to the end of March, sometimes even in April.

It grows to 80cm in length and up to 8kg in weight.

Chub – Leuciscus cephalus cabeda

Chub

It is a endemic member of the carp family, typical of the Adriatic river systems. It is similar to the chub from the Danube and its tributaries, which is why it was long called by the same name. Its body is long and round, covered in large scales. It lives in schools.

It inhabits the Soča from Kobarid down, the Nadiža, the mouth of the Tolminka, the Idrijca, the mouth of the Trebuščica and Bača. It is very numerous in the accumulation lake by Most na Soči.

It feeds on bottom-dwelling organisms, aquatic insects and plants, water-borne fruits as well as other fish in the case of the larger ones.

In our waters it spawns in May and June.

It grows to 70cm in length and 5kg in weight.

Italian barbel – Barbus plebejus

Like the chub it is a species of carp endemic to the Adriatic river systems. Just like the chub it was named the mrena, a relative from the Danube.

Barbel

Its body is long, slightly flattened at the flanks and covered with small scales, ending in a pointed head. It lives in schools.

It inhabits the Soča from Kamno down and the Nadiža. It is numerous in the Idrijca and in the accumulation lake by Most na Soči.

It feeds with bottom-dwelling organisms as well as aquatic plants.

It spawns in May and June.

It reaches lengths of 70cm and weights of up to 4kg.

Barbus meridionalis caninus

Besides the aforementioned species, which are interesting for anglers, our rivers are inhabited by the following species of smaller fish, which are not suitable for fishing, but are nevertheless important for the river ecosystems:

Mrenic – Barbus meridionalis caninus;
Blageon – Leuciscus souffia muticellus;
Whitefish – Alburnus a. alborella;
Minnow – Phoxinus phoxinus phoxinus;
River Bull-head – Cottus gobio.

More rarely seen, but nevertheless present, are the following species:

Linj – Tinca tinca
Adriatic roach – Rutilus rubilio aula
Rudd – Scardinius erythrophthalmus erythrophthalmus

Crayfish

We must also mention the crayfish which are found in our sector. In the Soča and its tributaries we find following species of crayfish: Austropotamobius italicus or Austropotamobius pallipes fulcisianus as well as Austropotamobius torrentium. The latter is present in the Idrijca and Bača, as well as their tributaries.