1. Please double check and update your email --> http://www.monsterfishkeepers.com/forums/index.php?account/contact-details
    Dismiss Notice

The "one inch per gallon" rule

Discussion in 'General Aquaria Discussion' started by guppy, Aug 30, 2007.

  1. guppy

    guppy
    Expand Collapse
    Small Squiggly Thing

    Real Name:
    Joined:
    Apr 15, 2005
    Messages:
    11,547
    Likes Received:
    9
    Trophy Points:
    0
    Occupation:
    right now none
    Location:
    confused, lost, and lonely
    Last Seen:
    May 11, 2008
    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.

    For small fish like glo-light tetras you will end up with something like this,
    1 1/2"x 1/4"x1/2", this comes to 3/16 of a gallon (about 1/5), and that gives you 5 fish of this size per gallon (quite reasonable)

    For larger fish you end up with something like this, my example here will be a silver arowana at 24" long, 24"x 4"x 1", which gives you 100 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.
     
    Collapse Signature Expand Signature
  2. cichlaguapote

    cichlaguapote
    Expand Collapse
    MFK Members

    Real Name:
    Joined:
    Oct 2, 2006
    Messages:
    8,982
    Likes Received:
    1
    Trophy Points:
    0
    Occupation:
    I wrestle flamingo's.
    Location:
    pripyat
    Last Seen:
    Nov 22, 2012
    Very enlightening. I never knew how that works. Through all the flaming always done I thought it was truly supposed to be 1" per gallon not 1 sq" per gallon. Great post.
     
    Collapse Signature Expand Signature
  3. rallysman

    rallysman
    Expand Collapse
    MFK Members

    Real Name:
    Joined:
    Aug 7, 2005
    Messages:
    17,509
    Likes Received:
    4
    Trophy Points:
    38
    Occupation:
    Clinical Engineer
    Location:
    indiana
    Last Seen:
    Nov 14, 2015
    Makes much more sense.
     
    Collapse Signature Expand Signature
  4. Mystix212

    Mystix212
    Expand Collapse
    MFK Members

    Real Name:
    Jake
    Joined:
    Jun 27, 2007
    Messages:
    4,984
    Likes Received:
    2
    Trophy Points:
    0
    Occupation:
    Aquatic Wholesaler
    Location:
    Brisbane, Australia
    Last Seen:
    Nov 21, 2013
    I get it much more thouroughly now. IMO I'd still feel safer to avoid the rule.
     
    Collapse Signature Expand Signature
  5. guppy

    guppy
    Expand Collapse
    Small Squiggly Thing

    Real Name:
    Joined:
    Apr 15, 2005
    Messages:
    11,547
    Likes Received:
    9
    Trophy Points:
    0
    Occupation:
    right now none
    Location:
    confused, lost, and lonely
    Last Seen:
    May 11, 2008

    I don't blame you but it does provide a nice general ballpark for planning a new tank or for someone lacking in experience.
     
    Collapse Signature Expand Signature
  6. JD_MAN

    JD_MAN
    Expand Collapse
    MFK Members

    Real Name:
    Joined:
    Aug 7, 2005
    Messages:
    2,498
    Likes Received:
    1
    Trophy Points:
    0
    Location:
    Your Mom's bedroom
    Last Seen:
    May 7, 2014
    I learned something new today! Thanks guppy!
     
    Layne Conitz likes this.
  7. ewurm

    ewurm
    Expand Collapse
    MFK Members

    Real Name:
    Joined:
    Jan 27, 2006
    Messages:
    28,340
    Likes Received:
    12
    Trophy Points:
    0
    Location:
    *
    Last Seen:
    Sep 14, 2014
    I thought it was 1 fish per inch.....No wonder my nitrates are so high.
     
    Collapse Signature Expand Signature
  8. guppy

    guppy
    Expand Collapse
    Small Squiggly Thing

    Real Name:
    Joined:
    Apr 15, 2005
    Messages:
    11,547
    Likes Received:
    9
    Trophy Points:
    0
    Occupation:
    right now none
    Location:
    confused, lost, and lonely
    Last Seen:
    May 11, 2008
    LOL
    Hey Ewurm, maybe that is why when you try to add a new fish it bounces,
    two more general rules, 1) it should take more than a teaspoon to do a water change, and 2) the tank should contain more water than fish.
     
    Collapse Signature Expand Signature
    Tyler_Wentworth_150 likes this.
  9. ewurm

    ewurm
    Expand Collapse
    MFK Members

    Real Name:
    Joined:
    Jan 27, 2006
    Messages:
    28,340
    Likes Received:
    12
    Trophy Points:
    0
    Location:
    *
    Last Seen:
    Sep 14, 2014
    That's why 20 water changes only takes 8 minutes.
     
    Collapse Signature Expand Signature
  10. snakehead121

    snakehead121
    Expand Collapse
    MFK Members

    Real Name:
    Joined:
    Feb 9, 2007
    Messages:
    69
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    washington
    Last Seen:
    Mar 31, 2008
    cool guppy, I have used a diffrent method befor. First you find the serface area (length by width). Then for your fish for tropical freshwater 12in. per 1in. of fish, for cold freshwater 28in.(I think it may be 20), and for saltwater 48in. And for fish that go to the serface to breath double the in. requierd.
     
    Collapse Signature Expand Signature

Share This Page