Bullhead - Cottus Gobio

About the Bullhead.
The bullhead is a miniscule species that does not feature on the list of popular freshwater fish that angler's most want to catch. However, it is a favourite with children who like to catch them in their nets.

This fish is often referred to as "miller's thumb" due to the shape of its head - broad and flat, as millers developed big, muscular thumbs from working the grain with their fingers.

Bullhead Identification

The bullhead, a member of the Cottidae family, is a very small fish that doesn't usually exceed 4 inches in length. The main part of its body is light brown and it is covered in darker brown patches and spots. Its underside is a pale cream colour.

It has a number of distinguishing features including its wide head, large eyes and thick lips. It also has two spiny dorsal fins plus a pair of huge fan-shaped pectorals.

Bullhead Habitat

The bullhead is found in many locations across England and Wales yet it is absent from Ireland and is only found in certain rivers and streams from the Forth and Clyde catchments in Scotland. It is not native to the UK and began to be seen in UK rivers during the 1980's.

As a freshwater species, the bullhead is found in freshwater rivers, streams and some lakes and has a preference for stony bottoms in fast - medium flowing shallow waters, mainly in upland regions, although it can be found in lowland rivers that are well oxygenated and unpolluted.

They spend most of the day hidden under rocks and stones, presumably to avoid predators such as pike, brown trout and various fish-eating birds, and only come out at night or early morning to feed.

Natural Bullhead Food

Bullhead emerge from their rocky hiding places when it is dark and dart along the bottom of the bed in search of food. Their main diet, particularly in the winter months consists of small crustaceans such as shrimp, whilst during the summer they feed on insect larvae and occasionally the larvae and eggs of other fish.

Bullhead Reproduction

Bullhead reproduce between the months of February and June depending on the temperature of the water. Curiously, it is the male bullhead that digs a hole or nest under an appropriate stone or tree root and then waits until he attracts a female. The female then deposits up to 400 eggs in the nest, which stick to the bottom of the stone. The male stays by the nest for several weeks until the eggs hatch, protecting them from predators by fanning the eggs with his large pectoral fins. This is also done so that the eggs receive plenty of oxygen.

During the reproduction process both male and female bullhead take on a different appearance. The male darkens in colour to almost black and his first dorsal fin takes on a creamy coloured edge. The female becomes plumper.

In warmer lowland waters where the temperature is higher than in its upland counterparts, the female is able to deposit up to four batches of eggs during one season.

Once the eggs have hatched the fry feed on their yolk sacs for ten days before they are ready to leave their spot and fend for themselves.

The Bullhead's Vital Statistics

  • Average weight: ½oz (14g)
  • Average length: 2 inches (5cm)
  • Life-span: Up to 5 years

Waters with big bullhead include:

  • Aire, Yorkshire
  • River Wharfe, Yorkshire
  • Ribble
  • River Dee, Wales
  • River Clough, Garsdale
  • Ure
  • Lake Windermere, Cumbria
  • River Trothy, Wales
  • Wye
  • River Lambourn, Berkshire
  • River Tweed, Scottish Borders

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