O. G. Dely szerk.: Vertebrata Hungarica 2/1-2. (Budapest, 1960)
Berinkey, L.: Ichtyological notes 1 11-18. o.
from the ventral fine to the aperture of the snaliB. Coregonus lavaretus maraena /BLOCH/ lives in the MadUsee in Pomerania. Owing to its many advantageous features, it waB introduced from there into several localities. There may be two explanations of the problem of its appearance in the reach at Vác of the Danube. The Balaton Pishing Company imported more than one million Coregonus albula LINNÉ spawns from Poland in 1958 and 1959, letting the fishes out, after hatching, into the Balaton. Therefore one, and, I may add, the less plausible, explanation is that the spawns, or at least some of them, imported from Poland, were not Coregonus albula LINNÉ, and that a part of the brood placed in the Balaton reached the Danube by way of the Sió Channel. The other, and more probable, explanation is that the fish arrived in the Danube from a country adjacent to Hungary, possibly from Czechoslovakia. SIMEK /11/ states in his book that Coregonus lavaretus maraena /BLOCH/ was successfully introduced in the lakes of Southern Czechoslovakia, they multiplied suitably, and then, for many years, specimens were placed out into free waters too. And from the rivers of Southern Czechoslovakia, the species might easily have reached the Danube. In my opinion,this is the most plausible explication of its occurrence in Hungary. Also, I have to point out an erroneous datum in SIMEK's book /p. 119-120/, namely that Coregonus lavaretus maraena /BLOCH/ originates from the Lake Tchud /originally Lake Peipus/. Rightly, the species lives in Lake Madii, while it is Coregonus lavaretus maraenoideB POLIAKOW which is indigenous in Lake Tchud, In every case, the occurrence of the species in the Danube is a most interesting ichthyo-faunistical datum. Salmo trut ta m. fario LINNÉ It is well-known that the brook trout is a typical inhabitant of the rapid, cold water, oxygen-rich mountain brooks, of the socalled trout-level. It occurs sometimes,
