goby (fish)
鯊 refers specifically to the goby, a small bottom-dwelling fish.
鯊 combines 魚 (fish) with 沙 (sand), likely indicating a fish associated with sandy environments, fitting the goby's habitat.
A fish 魚 that lives in the sand 沙: the goby hides in sandy bottoms.
For サ, imagine a goby fish swimming in the Sahara sand: Sahara -> サ, and the fish blends into the sand.
goby (fish)
southern Japanese mudskipper (Periophthalmus argentilineatus)
barcheek goby (Rhinogobius giurinus)
Myersina filifer (species of goby)
yellowfin toxic goby (Yongeichthys criniger); horny goby
Glossogobius olivaceus (species of goby)
flat-headed goby (Luciogobius guttatus)
mudskipper (Periophthalmus cantonensis); mudspringer
dusky frillgoby (Bathygobius fuscus)
yellow clown goby (Gobiodon okinawae)