I was surprised when I noticed this pink bud of the water lily plant (Nymphaea lotus var. pubescens/pubescens/esculenta) in my gold fish tub. I was not expecting it. Just because, I have never put any extra care for these plants - I kept them in my outdoor tubs for goldfishes and live-bearers, with minimum substrate and without any fertilization. Still it's flowering - I am happy, grateful too!
Red (pink) water lily or Nymphaea lotus var. pubescens is one of the most common aquatic plants found through out India. This is another easy-to-keep', to be precisely 'hard-to-kill' plant, but not actually suited for smaller indoor set ups. I haven't seen it flowering under artificial lightings in an indoor set up. But they do very well in outdoor set ups with direct and/or indirect sunlight.
The picture below, shows the lily in my goldfish tub, from top.