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,
Assessor flavissimus in crevices,often swimming upside down. The males mouthbrood, guarding the eggs in their mouths. Assessor flavissimus Assessor flavissimus, the yellow devilfish or yellow scissortail, is a fish from the western Central Pacific, recorded from the Great Barrier Reef]] and Papua New Guinea. It occasionally makes its way into the aquarium trade. It grows to a size of 5.5 cm in length. It is bright yellow in colour and has a reddish-orange stripe running from the eye to the upper edge of the operculum, and a reddish-orange band on the dorsal and anal fins which is parallel to the fin margin.