if its a 30 gallon standard, commonly 36" x 12" x 16"
if its a 30 gallon breeder, commonly 36" x 18" x 12"
if its a 30 gallon extra tall, commonly 24" x 12" x 24"
measurements are length x width x height in inches
exact measurements may vary slightly depending on the manufacturer due to glass thickness and whether they measure the inside of the tank or the outside of the tank.
90x35x55 is exactly 750 gallons and gives you just over 4 and a half feet in height with 7 and a half feet in length and almost 3 feet in width. There is no standard set of dimensions once you get this large though IMO.
Per Yankeecontainers.com: Exterior Dimensions in Inches
L: 18 5/8 Inch Outside Diameter
H: 29 1/8 Inch Outisde Height
72x24x24
That would be a standard 29 gallon aquarium
Its all your choice, my friend. However, the bigger the aquarium, the better the ecosystem- so I'd go with the 40 gallon. I have a 40 gallon fishtank myself.
The rule of thumb for stocking levels in a freshwater aquarium is 1 inch of fish per gallon of aquarium. For instance, five 1" guppies in a 5 gallon tank, or ten 3 inch cichlids in a 30 gallon aquarium.
A 30 gallon would be suitable if done properly for a tank up to about 125 gallons. Maybe 150.
At a Petsmart, Petco, aquarium builder, or a trusted pet shop
Depends on the size of the aquarium. Water weights 10 pounds per gallon.
no
You can put one maybe 2 one-inch fishes in your one gallon aquarium
For twenty small (1-1.5 inch) Goldfish you should have something like a 30 gallon aquarium.
Dimensions are 970mm high by 580mm diameter
A standard rectangle foot print aquarium of 50 gallons is: 36" x 18" x 19" However, 50 gallon tanks are less common than the 55 gallon tank and is normally inaccurately referred to as a 50 gallon tank and it has a foot print of: 48" x 13" x 21"