Making the assumptions that these measurements are in inches, and that the fish tank is a perfect cuboid, the volume of the fish tank is 49 x 19 x 21 = 19,511 cubic inches.
Rounded to two decimal places, this is equal to 70.47 gallons.
A good rule of thumb for fish placement is to try and equal inches of fish to gallons of water.
18.04
Filled to the brim it will hold a tiny bit less than 65 US Gallons. Allowing for the surface being about 1 inch from overflowing and also allowing for the displacement of water when gravel and rocks are added, your tank will actually be holding about 58 gallons of water when ready for fish.
A bit less than 75 US gallons.
Assuming you have proper filtration, you should abide by the one inch of fish per five gallons of water. This would mean a total of 13 total inches of fish.
Its a long explanation how but it should be about 25 gallons
It depends on the fish tank. They range from less than 2 gallons to over 300 gallons.
Multiply 36*12*16 = 6,912 cubic inches 12*12*12 = 1729 cubic inches per cubic feet 6912 cubic inches/1729 cubic inches per cubic feet - 4 cubic feet 4 cubic feet * 7.48051948 gallons per cubic foot = 29.90 gallons 7.48051948 Gallons per cubic foot
To find the volume of the fish tank in cubic inches, multiply the dimensions: 20 x 18 x 21 = 7560 cubic inches. To convert cubic inches to gallons, divide by 231 (since 1 gallon = 231 cubic inches). Therefore, a fish tank measuring 20 x 18 x 21 inches would hold approximately 32.8 gallons.
The tank has a maximum holding capacity of 25.45 gallons US. Filled to within 2" of the top it will hold 22.9 gallons US. For your future reference the calculation is " length in inches x width in inches x height in inches divided by 231.
A 12 by 27 hex fish tank holds approximately 30 gallons of water when filled to capacity.
No fish should be kept in a bowl. They should be kept in at least 10 gallons of water but usually more depending on how many fish you have and how many you have. A good general rule is for every inches of fish you should have 1 gallon of water keeping in mind that they will grow.