Pomatoschistus minutus
The sand goby (*Pomatoschistus minutus*) is a very small fish, but extremely abundant in shallow coastal areas. It is a master of camouflage, being almost invisible on sandy substrate. Although overlooked by most tourists, it represents a fundamental link in the beach ecosystem, being the main food source for the fry of many marine predatory fish and for wading birds.
The body is small, slender and slightly vertically flattened towards the tail. The colour is pale sandy-brown, with small darker spots and bright dots, perfectly mimicking the grain of the substrate. The eyes are situated on the upper part of the head and are oriented upwards. Like all gobies, the ventral fins are transformed into a sucker that allows it to remain fixed on the bottom despite wave movement.
It is widespread along European coasts. In Romania, it is present everywhere there is sandy substrate, from the beaches in the northern Delta (Sulina, Sf. Gheorghe) to Vama Veche. It frequently enters brackish lagoons and estuaries, being able to tolerate temporary drops in salinity.
The sand goby is a benthic fish that spends its time motionless or moving in short leaps. When threatened, it quickly buries itself in the sand using its pectoral fins. It actively feeds on tiny organisms in the sediments: copepods, amphipods, polychaete worms and chironomid larvae. It has more intense activity during periods of low light (dawn and dusk).
It has a very short life cycle, usually living only one or two years. Reproduction takes place in spring and summer. The male chooses a "nest" under an empty mussel shell or under a flat stone, where it attracts the female to lay her eggs. After fertilisation, the male guards the nest aggressively and fans the eggs until hatching. Many males die from exhaustion after the breeding season.
The species is Least Concern (LC). Populations are generally stable, but the species is sensitive to beach degradation through construction, dredging or microplastic pollution. It has no commercial value for humans, but conserving its sandy habitats is essential for maintaining coastal biodiversity.