Gardening Guppies

I am really confused. Quite honestly, I'm not sure how to even address the newest issue in my household. I feel betrayed.

No one told me that my new guppies have been gardening behind my back.

I opened the tank to feed the fish. I noticed something that resembeled an alfalfa sprout sticking out of the rocks in the bottom of the tank. Wha'...? There are no live plants in the tank, only plastic obvious-fake looking ones. So I thought!

After staring at this little live plant swaying happily in the fish poop water, I plucked it out.

A tomato plant. Growing. In the bottom. Of my fish tank.