Monday, November 19, 2007

Standard Size & Capacities for Fish Tank

The links below detail the main standard tank sizes which are available in the UK and the US, and which may also correspond to those available in other parts of the world. Remember that nominal capacities quoted for tanks are greater than the actual volume of water, due to the normal fill level being an inch or two from the top, depth of substrate and bogwood, rocks, etc used as decor. The volume may therefore be more accurately determined when filling the tank initially.

The stocking levels quoted have been based on two different systems which are used. The first is based on the volume of water required to support each fish. The second system is based on surface area of the tank, which, as it represents the area available for oxygen to dissolve into the water, is considered by some to be a useful indicator of maximum stocking levels. With this system, a deeper tank with the same base dimensions cannot hold more fish.

Remember, these are only guidelines, which work reasonably well for general community tanks as a rough guide, and a certain amount of common sense must be applied - you can't keep two 10" fish in a 20 gallon tank for instance! It is also sensible to understock the tank to allow a safety margin - it will be much easier to keep the fish healthy in a lightly stocked tank, as well as reducing the amount of filter maintenance and water changes that need to be done.

Standard UK Tank Capacities and Stocking Levels

The guidelines for stocking levels in the UK are usually based on either 1" of fish per UK gallon of tank water up to six months, and up to a max of 2" of fish per gallon thereafter, or calculated from 1" of fish per 12 square inches of surface area (note that this is not the same as 12 inches square!). Using the first guideline, your stocking capacity in total inches of fish length is equivalent to the volume in UK gallons below, or twice that as a max in a mature tank. The stocking levels based on surface area are quoted in the table - note that these usually give a higher number (except for tall tanks) than the volume calculation, and should be considered a maximum.

The tank capacities below have been calculated allowing for a fill level 1" from the top, and a 1" depth of substrate.

Tank SizeImp galUS galLitresMax. inches of fish based on
1" of fish per 12 sq." of surface area
18x12x12"
(45x30x30cm)
7.593418
24x12x12"
(60x30x30cm)
10124524
24x12x15"
(60x30x38cm)
13165924
24x12x18"
(60x30x45cm)
16197224
36x12x15"
(90x30x38cm)
20248936
36x12x18"
(90x30x45cm)
242910836
36x15x18"
(90x38x45cm)
303613748
48x12x15"
(120x30x38cm)
263111948
48x12x18"
(120x30x45cm)
323814448
48x15x18"
(120x38x45cm)
404818260
48x18x24"
(120x45x60cm)
657929772
48x24x24"
(120x60x60cm)
8710539696
60x15x18"
(150x38x45cm)
506022875
60x18x18"
(150x45x45cm)
597127090
60x24x24"
(150x60x60cm)
109131495120
72x15x18"
(180x38x45cm)
607227490
72x18x18"
(180x45x45cm)
7286324108
72x24x24"
(180x60x60cm)
131157594144
84x24x24"
(210x60x60cm)
153183693168
96x24x24"
(240x60x60cm)
174210792192

Standard US Tank Capacities and Stocking Levels

The guidelines for stocking levels in the US are usually based on either 1" of fish per gallon of tank water, or calculated from 1" of fish per 12 square inches of surface area (note that this is not the same as 12 inches square!). Using the first guideline, your stocking capacity in total inches of fish length is equivalent to the volume in US gallons below. The stocking levels based on surface area are quoted in the table - note that these usually give a higher number (except for tall tanks) than the volume calculation, and should be considered a maximum.

Dimensions
(LxWxH)
Volume in US gallons/typeVolume in LitersMax. inches of fish based on
1" of fish per 12 sq." of surface area
12x6x8"
(30x15x20cm)
2.5 mini96"
16x8x10"
(40x20x25cm)
51610"
20x10x12"
(50x25x30cm)
103815"
24x12x12"
(60x30x30cm)
155724"
20x10x18"
(50x25x45cm)
15 high5715"
24x12x16"
(60x30x40cm)
20 high7624"
30x12x12"
(75x30x30cm)
20 long7630"
24x12x20"
(60x30x50cm)
259524"
30x12x18"
(75x30x45cm)
2911030"
36x12x16"
(90x30x40cm)
3011336"
36x18x12"
(90x45x30cm)
30 breeder11354"
48x13x12"
(120x33x30cm)
33 long12552"
30x12x22"
(75x30x22cm)
3714030"
36x12x20"
(90x30x50cm)
3814436"
36x18x16"
(90x45x40cm)
40 breeder15154"
48x13x16"
(120x33x40cm)
40 long15152"
36x12x24"
(90x30x60cm)
4517036"
36x18x18"
(90x45x45cm)
5018954"
48x13x20"
(120x33x50cm)
5520852"
36x18x24"
(90x45x60cm)
6524654"
48x18x20"
(120x45x50cm)
7528472"
48x18x24"
(120x45x60cm)
9034072"
48x24x24"
(120x60x60cm)
12045496"
72x18x22"
(180x45x55cm)
125473108"
72x18x28"
(180x45x70cm)
150567108"
72x24x24"
(180x60x60cm)
180680144"

Acknowledgement: Thanks to Bill Kramer, OH, for info on standard US tanks sizes.

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