6 unusual facts you (probably) didn't know about fish

Rounder flounder

The flounder’s flat shape is unique. Born as a round fish, the flounder flattens out as it matures and settles onto its side on the sea bed. As they transition from tiny larvae into juveniles, their skull twists and one eye physically migrates across their head so that both eyes end up on the same side

'Doctor, Doctor'

Tench, sometimes called 'Doctor Fish' historically, have been thought to possess healing properties. Legend says that they rub their slimy bodies against other fish to cure disease. This even led to people boiling the mucus to use as a medicine for humans. Sadly though, it's just a myth.

Skimmers and slabs

Did you know bream are often referred to as 'skimmers' or 'slabs' depending on their size? Juvenile common bream (skimmers) usually weigh between 200g and 1.5kg. They are silvery in colour, exist in large shoals, and are popular in match fishing for building total weight. Slabs (or Dustbin Lids) are fully grown, mature adult bream usually weigh upwards of 2.5kg. They develop a dark bronze colouration, are bottom-feeders, and fight with heavy, plodding resistance.

Lady of the Stream

Nicknamed ‘The Lady of the Stream’ for its pretty colours, graylings easily negotiate fast currents as they search for their prey of small invertebrates.

Bonus fact: Grayling, when freshly caught, emit a faint, distinct scent of wild thyme, and is the origin of their scientific name Thymallus thymallus.

Superior vision

Did you know perch have amazing eyesight? Armed with porphyropsin (a photosensitive purple pigment found in the retinas of freshwater fishes), they're able to see remarkably well in dim lights and particularly in red hues, like at sunset. This gives them a brilliant advantage over their prey as they won't see them coming!

Fake pearls

In 1680, a Frenchman by the name of Jacquin had the idea of using a substance known as ‘essence of orient' from the scales of bleak to give man-made pearls their colour, which replaced the previous use of toxic compounds of mercury.

From 18,000 average sized bleak, around 7 lbs of scales could be scraped off and this quantity would produce a pound (450 g) of the essence orient. In the 18th century, Thames fishermen were major exporters of bleak scales to the French. Roach and dace scales were also used for this purpose but were not as highly prized as either bleak scales or the scales of whitebait.