it is a place where the fresh water merges with the sea water.
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics- mainly between latitude 25° N and 25° S.
Of course they can. Whether you're allowed to put them in the lake is a different matter, and I guess it depends what else is in the lake. But yes, they can survive and live in lakes.yes because it is freshwater fish