Water Lettuce And Other Floating Plants Dying

[Fullmoonnight]

Awhile ago my mom got me some floating plants like water lettuce, duck weed and some other plant I don't know( its like water lettuce but bulbs) they seem to be dying though. They are kept in a bin with fertilizer beside the window and no fish with them although I tried with one plant in my fish tank but it still turned yellow and died away.

 

[McKevlar]

How much light are they getting? Water Lettuce, for example, does well in high light conditions.

 

[Fullmoonnight]

How much light are they getting? Water Lettuce, for example, does well in high light conditions.

Erm well it's just beside the window in with no shades or anything getting in the way. Weather conditions over here are snowy but they started dying even before then.