Aponogeton boivinianus one in stock is big

Sold as a sprouted bulb/small plant
Aponogeton boivinianus will get large so a larger aquarium is recommended

A bulb plant from Madagascar, whose bulb may be covered with the bottom layer, as long as the sprout tip is at the soil surface. In favorable conditions it can form very large leaves (up to 80 cm long and 8 cm wide, and from 30-50 cm wide). The oldest leaves are deep dark-green, while younger leaves are light-green and sometimes brownish until they are fully developed. Nutrition capsules enhances the growth considerably.

It needs a dormant period when the bulb loses all its leaves, after which the growth will start again.