also crayfish and crabs, and since 2010s, the red-eared slider inhabits the lake, too, probably being released in the lake by the owners who kept them as pets. The freshwater jellyfish Craspedacusta sowerbyi was discovered in 2008, garnering much attention for the lake. These anthomedusae begin their life as polyps and develop into jellyfish only if conditions, such as purity and water temperature over 25 °C, are right. However, authorities claim that these harmless and almost invisible jellyfish (they are only to wide, bell is in diameter and have no sting cells) actually have been present in the lake for over 20 years. The first specimens were discovered in 1994 and they can also be found in the Danube. They live only for several days. Ada Safari Ada Safari () is a small, irregularly shaped lake on the northern tip of Ada Ciganlija, primarily used for fishing. In the late 1960s, the hole was formed as the sand was dug to construct the permanent embankment which connected Ada Ciganlija to the mainland, turning it into the peninsula by 1974. It was the last remaining marshy area during the transformation Ada Ciganlija, infested by undergrowth and reeds, until its conversion into a lake in 1994, long, with an area of . It was officially opened in 1995. The water pumps are used to fill the lake, bringing water from the Sava Lake. Rare species of fish were introduced in order to create a fishing resort, which now consists of 300 numbered fishing seats around the lake with an obligatory special permit for fishing. Fish species include common carp, grass carp, crucian carp, wels catfish, Prussian carp, zander and tench, which is rare in Serbia. Fish are mostly released back into the lake as fishermen can keep their catch in case if the fish is lighter than , if they pay extra and if it is not a tench, which is protected by the law. Some animals roam freely in the area, like rabbits, ducks, geese and swans. A small zoo has been built next to the lake, chiefly containing swamp birds, as well as more exotic animals such as peacocks, pheasants and pygmy goats. There is also a restaurant on the shore and a typical Serbian 18th century house from Šumadija which was deconstructed from the Central Serbia and transferred here. The house was originally built around 1735 in the village