Spined loach

Identification

The spined loach is a slender, elongated bottom-dwelling fish of 6 to 10 cm. The body is slightly laterally compressed with a row of prominent dark spots along the flank. Distinctive is the small, foldable spine below each eye — a defense mechanism unique to the loach family. Around the mouth are six short barbels (three pairs). The color is light brown to sandy with dark marbling. The difference from the stone loach: the spined loach is flatter, has the eye spine, and shows more regular spots along the lateral line.

Behavior & ecology

The spined loach lives buried in sandy or muddy substrate — only the head protrudes above the sediment. During the day it is virtually invisible; only at dusk does it emerge to forage on small worms, midge larvae, and organic material in the substrate. The species prefers still or slow-flowing water with a soft bottom and rich aquatic vegetation. When disturbed, it burrows with remarkable speed. Spawning occurs in May–June, with eggs deposited on water plants.

In the Netherlands

The spined loach is protected under the European Habitats Directive (Annex II) and Dutch nature conservation law. In the Netherlands, it occurs scattered across ditches, polder waters, ponds, and slow-flowing streams, particularly in peat bog areas and river clay landscapes. The species is an indicator for waters with a natural, undisturbed bottom and rich underwater vegetation. Populations are under pressure from dredging, bank hardening, and water pollution. The spined loach has no significance for sport fishing and is too small and rare to disturb.