Rotting water lettuce

[OscarRomeoFiveTwo]

Any ideas as why my water lettuce are rotting?

 

[Archerfish]

I'll take a guess here if it is in an aquarium: Either it was brought indoors from say, a pond and is not getting enough light or nutrients. If it is in a pond then what you are seeing is normal for the onset of the Fall season and winter. Or: It is getting 'sunburned' if it was indoors and suddenly brought outdoors.

 

[GaryE]

I have never been able to grow that plant indoors. Not many people can.

 

[Colin_T]

Do you have a cover on the aquarium?
If yes, it could be too humid for it. I have only ever managed to grow it indoors under very bright light and without coverglass.

Water Sprite is a better floating plant for aquariums and Water Lettuce is best left outdoors.