Balon, E. K., S. S. Crawford and A. Lelek (1986).  Fish communities of the upper 
Danube River (Germany, Austria) prior to the new Rhein-Main-Donau connection. 
Environmental Biology of Fishes.  15:243-271.
	
A study of fish communities in the upper Danube was carried out at 19 localities 
in 1976 and 1984, yielding 24 samples with over 23,000 specimens. Forty-two 
species - 8 of them new for this part of the Danube - and 6 cyprinid hybrids 
were identified. Two distinct regions, above and below Ulm, were recognized for 
the upper Danube on the basis of both abiotic (distance from source, elevation, 
river gradient) and biotic (species richness, species distribution) characters 
of the localities. Nine species were distributed over most of the upper Danube, 
while 10 and 23 species were limited mostly to the upriver and downriver 
sections, respectively. A factor analysis of ecomorphological attributes for 28 
dominant species revealed a generalist-specialist pattern among their swimming 
behavior and feeding modes.