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
Demersal fish benthic fish are denser, with negative buoyancy so they can lie on the bottom without any effort. Most demersal fish are benthopelagic. As with other bottom feeders, a mechanism to deal with substrate is often necessary. With demersal fish the sand is usually pumped out of the mouth through the gill slit. Most demersal fish exhibit a flat ventral region so as to more easily rest their body on the substrate. The exception may be the flatfish, which are laterally depressed but lie on their sides. Also, many exhibit what is termed an "inferior" mouth, which means that the mouth