Old aquarium 30x12 inches x18 inches high (standard 29 gallon size). It does hold water, but the glass is permanently hazy, so this wouldn't work well for fish (unless you don't care about seeing them!). If you want a screen lid for the tank, I can include that.
We received this from a fellow Freecycler a while back, who had used it as a fish tank, and we used it for a period of time for a bearded dragon. We no longer have the bearded dragon and would love to find a new home for the tank and stand. The dimensions are (approximately) 50" tall, 36" wide, and 13" deep at the corners and 16.5" at the middle where it is curved out..... And it's hard to tell...