RV Platessa the central basin. The RV "Platessa" (LT205) was in service with Ministry of Agriculture, Fisheries and Food (United Kingdom) from April 1946 until June 1967, during which time she participated in more than 473 separate research campaigns. She was primarily confined to the southern North Sea, but with occasional forays into the Irish Sea and English Channel, especially in the 1960s. The RV "Platessa" (LT205) was overwhelmingly dedicated to research on North Sea herring and North Sea Plaice. This work included the tagging of more than 12,000 plaice during the 1950s, 7000 during the 1960s. In addition, large numbers of
Flatfish around "ponds" of sulphur at hydrothermal vents on the seafloor. No other flatfish is known from hydrothermal vents. Many species will enter brackish or fresh water, and a smaller number of soles (families Achiridae and Soleidae) and tonguefish (Cynoglossidae) are entirely restricted to fresh water. The most obvious characteristic of the flatfish is its asymmetry, with both eyes lying on the same side of the head in the adult fish. In some families, the eyes are usually on the right side of the body (dextral or right-eyed flatfish), and in others, they are usually on the left (sinistral or left-eyed