|Lake Toba is a large natural lake in Indonesia located in the super volcano caldera. It is estimated that Lake Toba was formed during an explosion around 69,000-77,000 years ago and is the most recent supervolcano (super volcano) eruption.
The flora in the lake includes various types of phytoplankton, small macrophytes, floating macrophytes, and immersed macrophytes, while the surrounding land is covered with rainforests, including the types of tropical pine forests of Sumatra in the higher mountain areas.
The fauna in the lake includes several species of zooplankton and benthic animals. Because the lake is oligotrophic (not rich in nutrients), the original fish is classified as rare. There are only two fish endemic to this lake, namely Rasbora tobana (can be called almost endemic because it is also found in rivers that empties into this lake) and Neolissochilus thienemanni, commonly called Batak fish. The latter species are threatened by deforestation (causes of siltation), pollution, changes in water levels, and new fish species brought to this lake. Other native fish species are Aplocheilus panchax, Nemacheilus pfeifferae, Homaloptera gymnogaster, Channa gachua, Channa striata, Batrachus Clarias, Barbonymus gonionotus, Barbonymus schwanenfeldii, Danio albolineatus, Osteochilus vittatus, Puntius binotatus, Rasbora jacobsoni, Tor tambra, Betta imbellis, Betta taellata, Betta taeniata, and Monopterus albus. Migrant fish species include Anabas testudineus, Oreochromis mossambicus, Oreochromis niloticus, Ctenopharyngodon idella, Cyprinus carpio, Osphronemus goramy, Trichogaster pectoralis, Trichopodus trichopterus, Poecilia reticulata, and Xiphophorus hellerii.…