Identification
An elongated, eel-like fish of 15 to 25 cm, strongly laterally compressed. Characteristic row of 9 to 15 dark, white-rimmed spots along the dorsal fin base. Yellowish-brown to reddish-brown. Smooth, slippery skin — hence 'butterfish'.
Ecology
Lives in the intertidal zone under stones and among mussels. Tolerates exposure at low tide. Guards egg clusters under stones in winter.
In the Netherlands
Found on hard coasts: groynes, dykes, and harbor walls. Common in Zeeland and the Wadden Sea.
