Stagnant waters represent important habitats for many plant and animal species, particularly lakes and swamps which occupy large areas. Two pools in the aquarium represent a marsh and a swamp. Marsh is, as a rule, more shallow than a lake, usually forms next to rivers or in flooded areas. Sunlight in marshes usually reaches the bottom. Swamp is the most shallow stagnant water with a large amount of vegetation and high biodiversity. It forms in the place of former lakes and marshes and on meanders of rivers which changed their course. Besides fish such as tench, roach and rudd we can encounter reptiles (turtles and snakes), amphibians (frogs) and newts.