The plant is Syngonium.
There are several species with slightly different leaf shapes, and many varieties with different leaf colors.
One of them is almost pure white, with a few green speckles. Another is slightly greener, not really pure white, but close.
Another is sort of tinted red, not a lot, just a wash of red over the green.
Several are a blend of green background and various patterns of white, cream or yellow speckling and banding.
I have one that has more distinctly angled leaves. Like larger arrowhead shape, large back parts, then it got bent sideways like wings. The leaves are about a foot across. It is growing out of the top of my 72 gallon tank, and has reached the floor and is growing back up again. Really big! It started form a 4" potted house plant, just about the same as yours. Different species, though. Mine is pure green, deeper cut lobes.
I also have a tank with a set up sort of like that. The water runs the full length, though, not back to front. I have Heartleaf Philodendron in it now. At different times I have grown a really nice Prayer Plant (Purple veining, not the plain Rabbit Tracks species), and several other plants.