Bony fish · Scorpaeniformes · Cottidae

Bullhead

Cottus gobio

Least Concern

The species is abundant and widely distributed; it faces no significant short-term risk. See full glossary

It has no swim bladder at all, which gives it the negative buoyancy that suits its life on the bottom. The male is an extraordinarily dedicated father, guarding and fanning the eggs throughout incubation.

Weight

6 g – 28 g

Size

8 cm – 18 cm

Lifespan

4 years

Diet

Carnivore

Feeds mainly on other animals.

Activity

Nocturnal

Active mainly at night.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Easy

FreshwaterCarnivore Nocturnal Solitary Fish Freshwater

5countries1same family

Fun facts

It has no swim bladder, which suits its life pressed against the riverbed.
The male guards and actively fans the eggs throughout incubation.
When food is short the male may eat his own clutch.

Life cycle & biology

Skeleton type: Vertebrate - internal bony skeleton (fish)
Habitat & environment: Fast, cold, well-oxygenated rivers and the rocky shores of cold lakes across much of Europe, from Scandinavia to Italy
Birth weight: Eggs laid under stones; a tiny larva on hatching
Size at birth: A tiny larva on hatching; tended and defended by the male until then
Sexual maturity: Not precisely known (maturity is reached in the first or second year)
Gestation / incubation: Several weeks of egg development, watched over and actively fanned by the male
Litter / clutch size: 100 to 500 eggs per clutch

Sources consulted: The Wildlife Trusts; Natural England (Ecology of the Bullhead); FishBase; Website of Everything; Grokipedia; Wikipedia (European bullhead); Fishipedia