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,
Crazy fish of the fins can turn paler (to either orange or white), accompanied by the appearance of numerous reddish spots on the lower half of the body. The upper half of the caudal fin also turns white. Crazy fish are caught and sold for the aquarium trade. They are also edible and are sometimes fished for human consumption. They are reasonably abundant and are classified as Least Concern by the IUCN. Crazy fish Butis butis, the crazy fish, duckbill sleeper, or upside-down sleeper, is a species of sleeper goby that are native to brackish and freshwater coastal habitats of the Indian