Aega antarctica fish. It has strong muscles in its oesophagus and large salivary glands and rapidly fills its dilatable hind gut with blood. It then drops off the fish and spends several months on the seabed digesting the blood. In a research study, specimens of "Aega antarctica" were kept in a marine aquarium at the University of Oldenburg, Germany, where they were maintained at a temperature of . It was found that they would feed on a number of species of fish native to the North Sea and in this research they were fed on live European plaice ("Pleuronectes platessa"). One fish
Flatfish be a valid species in its own right. Flatfishes are found in oceans worldwide, ranging from the Arctic, through the tropics, to Antarctica. Most species are found in depths between 0 and , but a few have been recorded from depths in excess of . None have been confirmed from the abyssal or hadal zones. An observation of a flatfish from the Bathyscaphe Trieste at the bottom of the Mariana Trench at a depth of almost has been questioned by fish experts, and recent authorities do not recognize it as valid. Among the deepwater species, "Symphurus thermophilus" lives in congregating