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,
Pseudorhombus arsius Pseudorhombus arsius Pseudorhombus arsius, the largetooth flounder, is a species of left-eyed flatfish, that is the dark side with the eyes on the adult fish is the left side of the fish's body, from the family Paralichthyidae. As "Rhombus polyspilos" it was named as the type species of the genus "Pseudorhombus". It is an Indo-Pacific species and is fished for by both recreational and commercial fisheries. "Pseudorhombus arsius" has an oval-shaped body which has a depth which is 1.8 to 2.3 times its standard length. The head has a slight notch in front of upper eye. The eyes are on