The "one inch per gallon" rule

[boledle]

makes sense... you compare 20" gar with a 20" red tail cat and you've got about 6x more fish and a lot more water needed with the cat.

 

[Danyal]

ok, so the cubic incher per gallon rule seems to work somewhat well for a good number of fish(although 5 glowlights per gallon is rediculous, imo) but you still can end up overstocked or understocked. in the example of a jack dempsy needing a 60g tank, that works well for determining how large of a tank the JD is going to need when fully grown but you've also got a good amount of room for more fish, i doubt anyone if going to put just 2 JDs into a 120g or just one in a 60g. and the betta in a 4.5g is great however they can do well in somewhat smaller tanks(1g is the absolute min imo) and in a 4.5g you'd have room for a few other fish, depending on the demensions and how much cover is in the tank, and whether or not the betta is aggressive to other fish.

 

[vlindertje]

This is something that comes up fairly often and is rather misunderstood therefore I will attempt to clarify the original meaning of the general guideline of "one inch of fish per gallon of water".

This is a suggested guideline for a well maintained and filtered tank.
It does not apply to all fish as some have differing requirements.

Here is the part that is being misunderstood.

The "rule" does NOT refer to the length of the fish!

The "rule" applies to the cubic inches of fish in the tank.

This means that a 5" gourami should be measured in this manner,
length overall (5"),
thickness, (1/2"),
height, (2 1/2"),
so for this fish you multiply the following, 5x 1/2x 2 1/2, this gives you a total of 6 1/4 gallons of water.

As you can see this works fairly well.

You do also have to apply some common sense and allow for such things as potential growth, the fish types' tolerance for crowding, and of course the width and length of the tank (a 24" gar will not work in an 18" wide tank even if the tank holds 100 gallons).

So please people, accept that this is just a generalized guideline to figure potential stocking levels, not a hard and fast rule.
Also remember that just because you don't like it doesn't mean you should slam somebody for using it.
And lastly, please don't flame someone by saying a 10" oscar doesn't fit in a 10" tank.
Of course it doesn't,
but the rule never said it would.

This makes much more sense than the "normal" way this rule is always applied, i have never met anyone that calculated it this way though.

Also i have seen that even some small fish need a huge territory and can be very agressive (the "lovable" platy ) and some bigger fish can do with relatively less.

Anyway i guess having monsterfish includes having monstertanks so this problem shouldn't exist here, right?

 

[Brackishbandit]

It is not that complicated if you look at the projected size that your fish will grow. You will see this as not a rule just a half as* wal mart fish sales men "rule", why waste time on measuring "inches,cubic inches,displacement" just read up on fish growth rate and there natural environment. Fill your tank or upgrade to larger tank as fish grow. This is not a rule for any one to pass or use if you want any fish success.

 

[Danyal]

just read up on fish growth rate and there natural environment. Fill your tank or upgrade to larger tank as fish grow. This is not a rule for any one to pass or use if you want any fish success.

that's pretty much my feelings on the issue but so many people demand that there be a rule that works that it gets tiresome explaining that every fish is different and going to have different needs. at least this one is a lot better than the usual inch per gallon.

 

[andiefusco]

i was under the impression that the determining factor in the ratio was surface area of the tank while putting into consideration how much water was displaced by the fish. i think that keeping a fish in a hexagonal tank is very much different than the standard rectangular one. please correct me if i'm wrong, i hope everyone has the best interest of their fish in mind, but it must be considered how much oxygen is getting circulated in your system before adding new friends to the equation.

 

[Danyal]

if you've got a good W/D filter or something that provides a lot of aeration then you don't have to worry about oxygen levels.

 

[Kdcarey]

howw bout just judge by how much water ur fish need to swim?

 

[rareasabluemoon]

The rule never made sense to me. A 10 inch oscar in a 10 gallon tank didn't sound right. Seemed like they needed a 20-30 gallon tank, and your explaining of the rule equals that

 

[barrakooda]

I definitely don't agree with the 1 inch per gallon tank rule... I've got about 50 fish in a 30 gallong planted community tank and each fish is minimum 1 inch up to 3 inches for a black ghost knife!