Age determination in fish fish. Johannes Reibisch, working for the Commission of Scientific Investigation of German Seas at Kiel, attempted to use Hoffbauer’s techniques to age plaice ("Plueronectes platessa") but found it difficult to accurately discern annuli. He decided to study a different structure and in 1899 he published the first procedures using otoliths as an aging structure. A fellow scientist also with the German Commission at Kiel, Friedriche Heincke, also frustrated with difficult scale annuli, further studied other structures to age fish. He discovered annuli in the vertebrae, opercula, and pectoral girdle and published his findings in Heicke 1905. The works of Hoffbauer,
Ide (fish) of other cyprinids, but the larger adult fish form smaller single species groups which patrol what are believed to be regular routes. The ide prefers clear, warmer water and is not as tolerant of eutrophication as some related species. Ide spawn in running water and this means that the obstruction of rivers by dams and other man-made objects can negatively affect this fish. As an ornamental fish the ide is usually referred to as the orfe and the main variety kept is the golden orfe, which is golden or orange in colour with some black spots on its neck, near