The Underwater Nature stamps depict a chub (fish) and a water gentian (plant). The chub (Rhodeus amarus) is a small plant-loving fish with a highly built, laterally flattened body. The males have a purplish-red glow in the spawning season. For reproduction, the chub seeks out a live freshwater mussel and lures a fertile female to it. She lays her eggs in the gill cavity of the mussel, after which the male releases his roe at the inlet opening. The Dutch name for the chub (bittervoorn) comes from the bitter taste of its flesh, probably a repellent against predatory fish.
