The bullhead 

The bullhead is a small fish that has neither a swim bladder nor scales. It is not very popular among anglers. Due to its small size, it is not suitable as a fish for food. In addition, it was long considered a feared fish spawn predator. In fact, it mainly feeds on river fleas, insect larvae and snails. It lives on the bed of the body of water and is nocturnal. During the day it hides under roots and dead wood, which is why it is extremely seldom observed from the bank.

In spring, the males create a spawning pit in protected areas in the stream bed. The females lay their eggs there, which are then fertilised by the males. The eggs are guarded by the male until they hatch. After hatching, the young bullheads drift downstream through the current. Only when they are of a certain size are they able to move against the current to other sections of the stream upstream.

If transverse structures such as barrages are installed in bodies of water, they present an insurmountable obstacle to migration for the bullhead living on the bottom. For this reason, the dismantling of such systems and the renaturation of flowing waters is of great importance for the bullhead, but also for other inhabitants of streams and rivers. 

Groppe (Foto: H. Arjes)