This item is a Yee pneumatic aquarium incubation and breeding box, model YSL-506. It is designed for isolating, breeding, and raising aquatic pets like fish or shrimp.
The pneumatic design typically uses an air pump to circulate water through the box.
It serves as a safe hatchery and spawning chamber to protect eggs and fry from predators.
The large size (大号) provides ample space for nurturing young aquatic life.