Thymallus Aeliani.
Species description.
Thymallus Aeliani or Adriatic grayling as it is known is a grayling species found in northern part of the Adriatic River basin. Its easily recognised by its large dorsal fin that can is blueish grey. It has light grey sides with sometime some yellow and its tail is yellow orange. With a maximum length of 60cm and a weight of 6.5KG its a medium sized salmonid. Large fish sometimes feed on a small fish but this species mostly feeds on aquatic insects and other insects. Its a cold-water lover and is found in deep pools with a bit less flow.
Behaviour.
Grayling are found in deep slow flowing pools and its outflow and are mostly found near the bottom of the river. They feed larva, aquatic insects, bugs, ants and other insects, when the conditions are right, they also feed on the surface. They can be recognised by their calm movement and position in the river. And in colder times they tend to school together.
History.
Throughout history grayling have inhabited large parts of Europe but humans started to kill these beautiful fish because it was thought they competed with trout for food and they would keep trout out of some parts of the streams. Recent findings are that they feed on different items and they inhabit different micro habitats than trout. Some research even found that streams with good grayling populations have better trout populations as well.
Threats.
Grayling populations in a lot of its habitat are declining and under pressure. Declining water quality and an earlier end to the snow melt period might be some of the causes to this decline. This together with dams splitting populations, habitat destruction and there might be other things that play a roll as well. For the Adriatic grayling there is also the threat of hybridising with the European grayling which happened in a lot of its native habitat.
Distribution.
The Adriatic grayling is native to Italy, Slovenia and Switzerland. At this moment only in Italy there are relatively pure populations to be found in some parts of the Po River basin. Other populations are hybridised.