Flatfish are usually born round like other fish but soon develop a flat shape and swim on one side close to the bottom, with their skull bones twisting so that both eyes move around to one side of the body facing upwards. As well as the flounder, which is found in estuaries and in the lower reaches of rivers, there are several species of flatfish found around Ireland's coast that are caught by sea anglers:
Plaice (Pleuronectes platessa)
Plaice usually have a brown upwards side with vivid orange or reddish spots, smooth skin and a row of bony knobs just behind their heads. Adult plaice are predators of bottom-dwelling worms, crustaceans, molluscs and fish. They are found in estuaries, usually on sand but also often on mud or gravelly bottoms, and they are particularly associated with mussel beds.
Dab (Limanda limanda)
Dab usually live at depths of 20-40m, but adults migrate inshore in spring and summer months, and young dab are abundant in shallow, sandy areas. Usually a sandy colour with black and orange flecks, dab are best identified by touch: their rough scales feel like sandpaper when rubbed along their back towards their head. The lateral line running down the back is curved just behind the head in dab. Dab eat bottom-dwelling worms, crustaceans and molluscs.
Turbot (Scophthalmus maximus)
Turbot have bodies shaped like a rounded diamond that are usually a well-camouflaged mottled, brown sandy colour on their upwards side, with bony knobs in their skin. They prefer to inhabit shallow, sandy areas, and adults are active predators of bottom-dwelling fishes, such as sandeels. Turbot are highly regarded by sea anglers as a delicious fish for the table.
Brill (Scopthalmus rhombus)
Brill are similar to turbot with very round, almost circular bodies, but they do not have bony knobs under their skin. Part of their dorsal fin near their mouth has a frill-like appearance. Brill are usually caught off beaches in summer in Irish waters, but they have become scarcer in recent years. Like turbot, they are predatory and like to eat fish.
Halibut (Hippoglossus hippoglossus)
The largest flatfish in the world, the halibut can grow to monster sizes, and the current Irish record is 70.8kg. Halibut have a relatively long, thick body for flatfish, with a large, toothy mouth. Halibut are active predators of many kinds of fish, and unusually for a flatfish, they sometimes hunt in mid water as well as on the bottom. They prefer to live in cold northern waters and are a rare catch off the coast of Ireland.
Megrim (Lepidorhombus whiffiagonis)
Rarely caught by sea anglers in Irish waters, the megrim usually lives at depth on muddy bottoms on the continental shelf. They can be recognised by their relatively long, oval, pinkish brown bodies and large, extensible mouth.
Common sole (Solea solea)
Also known as black sole or Dover sole, the common sole can be distinguished from other flatfish by its distinctly oval-shaped body and smooth, almost slimy feel. Although rarely caught by anglers compared with other flatfish, they are valued as a delicious fish for the table. Sole usually move inshore to sand and mud banks in summer and autumn and feeds on bottom-dwelling worms, crustaceans, molluscs and small fish.