Here is the measurements for single hexagon fish tank:
Used 50 Gallon plexi glass hexagon fish tank for sale. Tank is light and
durable, easy to carry. Measurements: 14.5 inches Wide, 24 inches height, face
to opposite face 25 inches.

Here is description for double hexagon fish tank.
Used two 25 Gallon plexi glass hexagon fish tank connected by two hollow tubes
for sale. Fun seeing fish swimming between two tanks. Measurements for each
tank: 10.5 inches Wide, 20 inches height, face to opposite face 18 inches, total
length 42 inches.