|  |  | | 
January 21st, 2009
|
| | Fish Bum
| One Inch Per Gallon Rule?
Hey there! I've heard some conflicting information about the inch per gallon rule. Specifically, that it doesn't refer to length, but actually sq. inches of fish. This is a sticky over at the Monster fish Keepers forum, and I wanted to hear some opinions about it. This was written by the user "Guppy." Quote:
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.
| What do you all think about that? It seems to make sense, but then again I am very, very new to fishkeeping. I'm a bit confused... | 
| | |
January 21st, 2009
|
| | Moderator
| We've had the discussion before, and the cubic inch thing works better, but it still isn't perfect.
Around here, we call it (or try to) the "one inch per gallon guideline," and we generally only apply it to small, commonly-kept community fish. Even going with the cubic inch, there are fish that don't fit it either due to biology or personality (think bettas)
To go with Guppy's example, a 2' long arrowana would be absolutely miserable in a 100g tank. It wouldn't even be able to turn around without bumping into the side of the tank.
To go with another example of Guppy's, I certainly wouldn't want to cram 50 fish of any kind, even the glowlight tetras, into a 10g tank.
As you can see, there is a bit of a failure in Guppy's logic. (sorry, I couldn't resist mimicking that)
The reason we call this concept a guideline is that there is more information involved in the stocking process than the simple idea of size.
Last edited by sirdarksol; January 21st, 2009 at 02:41 PM.
| |
| | |
January 21st, 2009
|
| | Fish Helper
| It does make sense, but I am in the same boat as you, being a newbie and all! It would be nice if there were a more scientific guideline out there that gave us info on the volume of ammonia each type of fish produced... | |
| | |
January 21st, 2009
|
| | Moderator
| Quote:
Originally Posted by docjr03  It does make sense, but I am in the same boat as you, being a newbie and all! It would be nice if there were a more scientific guideline out there that gave us info on the volume of ammonia each type of fish produced... | There is, but the problem is that it takes into account several factors that make it difficult to put down as a simple formula. It involves the fishes' diet, their size, the biology of the species (different animals possess differences in digestive efficiency), etc... That's why, in the end, the best way is to research the individual species when you're making a decision on what to add. | |
| | |
January 21st, 2009
|
| | Fish Keeper
| I have found that there are a million (ok...a lot) different methods for calculating EXACTLY how many fish you can put in such and such a tank - figuring out what to do can be incredibly confusing! The danger with these methods, as sirdarksol said, is that they don't take into account many things more important than the actual size of the fish - like temperament, behaviour, bioload etc. They also don't factor in things like how much decor you have (more decor, less actual water) or maintenance.
All that said, I always feel it's dangerous in any situation to over-science-ize something, as in putting too much importance on some calculation. The best method (I've found) is to START with the 1"/gallon guideline and come up with a list of what you think will work, then ask more experienced fishkeepers what they think of it. As you become more experienced, you'll be able to determine for yourself what will work and what won't. | |
| | |
January 21st, 2009
|
| | Fish Helper
| Quote:
Originally Posted by prairielilly I have found that there are a million (ok...a lot) different methods for calculating EXACTLY how many fish you can put in such and such a tank - figuring out what to do can be incredibly confusing! The danger with these methods, as sirdarksol said, is that they don't take into account many things more important than the actual size of the fish - like temperament, behaviour, bioload etc. They also don't factor in things like how much decor you have (more decor, less actual water) or maintenance.
All that said, I always feel it's dangerous in any situation to over-science-ize something, as in putting too much importance on some calculation. The best method (I've found) is to START with the 1"/gallon guideline and come up with a list of what you think will work, then ask more experienced fishkeepers what they think of it. As you become more experienced, you'll be able to determine for yourself what will work and what won't. | Well said...  | |
| | |
January 21st, 2009
|
| | Fish Bum
| Thanks for weighing in, everyone! I thought the tetra thing seemed a bit over the top. Can you imagine 100 tetras in a 20 gallon tank?  | |
| | |
January 21st, 2009
|
| | Fish Helper
| Quote:
Originally Posted by Didgeridoo Thanks for weighing in, everyone! I thought the tetra thing seemed a bit over the top. Can you imagine 100 tetras in a 20 gallon tank? | Imagine  ? I have 102!  | |
| | |
January 21st, 2009
|
| | Fish Master
| When stocking... well, I usually have species tanks, so that makes it easy. But, if I were going for a community, I start with only a few fish. Then wait a while, add a few more. I keep an eye on the water quality. As long as the fish have the proper space, just watching the nitrates should tell you when you're fully stocked. With all of my tanks I can get away with water changes every other week (although I usually do it weekly anyways). For example, my 10g tank. If you look at it in my aquarium info in terms of fish it's quite overstocked. But, they all have sufficient room, and I never see nitrates over 10ppm, even if I let it go 2 weeks between water changes.
So, I say, forget the rule, figure it out through experience!  | |
| | |
January 21st, 2009
|
| | Fish Helper
| FLOG THE SCURVY DOG  | |
| | |
January 22nd, 2009
|
| | Fish Keeper
| Quote:
Originally Posted by pinkfloydpuffer When stocking... well, I usually have species tanks, so that makes it easy. But, if I were going for a community, I start with only a few fish. Then wait a while, add a few more. I keep an eye on the water quality. As long as the fish have the proper space, just watching the nitrates should tell you when you're fully stocked. With all of my tanks I can get away with water changes every other week (although I usually do it weekly anyways). For example, my 10g tank. If you look at it in my aquarium info in terms of fish it's quite overstocked. But, they all have sufficient room, and I never see nitrates over 10ppm, even if I let it go 2 weeks between water changes.
So, I say, forget the rule, figure it out through experience! | Although still new myself this is exactly the “science” I am planning to use. I have a 35 gallon tank and will be stocking it with very small fish so I know room to swim and turn around will not be a problem.
Currently I only have 6 neons, 1 clown pleco and an apple snail. My nitrates never get over 5ppm so I know I’m far from my stocking limit.
I will continue to stock a few fish at a time until I find my nitrates reaching 10 to 15ppm in a week. I will be able to control this with water changes.
Of course I am also considering the habits of the fish I will be adding (where they swim in the tank). I wouldn’t use this method and stock my tank with fish that are only middle swimmers. Then over crowding could become a problem.
So my pleco keeps to the bottom of the tank. The neons are right there in the middle of the tank. And my next addition will be 2 honey gouramis that like to hang out near the top of the tank. And as far as the apple snail well he’s just every where. | |
| | |
January 22nd, 2009
|
| | Fish Keeper
| Great points everybody!
Here's how that formula would apply to our 4'' Chinese Algae Eaters:
2x(4x1/2x1/2) = 2 Gallons
Two 4-inch CAE's in a 2 gallon tank HA! In the case of long skinny fish, it's safer to go with one inch of length per gallon of water. This would bring us to 8. Much better, but not even close to what two CAE's need due to their bio-load and swimming habits. | |
| | |
January 22nd, 2009
|
| | Fish Mentor
| Quote:
Originally Posted by dancerhas Great points everybody!
Here's how that formula would apply to our 4'' Chinese Algae Eaters:
2x(4x1/2x1/2) = 2 Gallons
Two 4-inch CAE's in a 2 gallon tank HA! In the case of long skinny fish, it's safer to go with one inch of length per gallon of water. This would bring us to 8. Much better, but not even close to what two CAE's need due to their bio-load and swimming habits. | No kidding! CAE's are HUGE fish in a small body! I don't think I would keep one in anything less than a 40 gallon. And if there were two, then I would go with a 75 gallon or larger. | |
| | |
January 22nd, 2009
|
| | Fish Keeper
| I wish people would stop looking into "rules" for stocking fish, none are accurate enough to be worth following them. Really, common sense is the best guideline... | |
| | |
January 22nd, 2009
|
| | Moderator
| Where's Amanda? She dislikes the 1" rule too.
Personally, I like to use it as a guideline, not a rule and only for small non bulky fish. To me, it helps to give new fish keepers something to go on and avoid overstocking a smaller tank.
After someone gets a good understanding of the nitrogen cycle, swim space and compatibility then they'll know what their tank can and cannot handle. | |
| | |
January 22nd, 2009
|
| | Fish Helper
| Quote:
Originally Posted by pinkfloydpuffer When stocking... well, I usually have species tanks, so that makes it easy. But, if I were going for a community, I start with only a few fish. Then wait a while, add a few more. I keep an eye on the water quality. As long as the fish have the proper space, just watching the nitrates should tell you when you're fully stocked. With all of my tanks I can get away with water changes every other week (although I usually do it weekly anyways). For example, my 10g tank. If you look at it in my aquarium info in terms of fish it's quite overstocked. But, they all have sufficient room, and I never see nitrates over 10ppm, even if I let it go 2 weeks between water changes.
So, I say, forget the rule, figure it out through experience! | Couldn't think of a better way to do it. PFP seems to have it down!  
(I will be using this method when I finally get to start stocking my tank thanks to her advice previously!) | |
| | |
January 22nd, 2009
|
| | Moderator
| Quote:
Originally Posted by Lucy Where's Amanda? She dislikes the 1" rule too.
Personally, I like to use it as a guideline, not a rule and only for small non bulky fish. To me, it helps to give new fish keepers something to go on and avoid overstocking a smaller tank.
After someone gets a good understanding of the nitrogen cycle, swim space and compatibility then they'll know what their tank can and cannot handle. | Well said. This is pretty much where I'm coming from when discussing such guidelines. | |
| | |
January 23rd, 2009
|
| | Fish Mentor
| The best stocking rule i've found is to combine the 1 inch guideline with common sense. I have a 75gal tank with 24 inchs of fish, the 24 inchs come from 2 Oscars though and I wouldn't put them in a 24gal tank! I also have a 20gal with about 26 inchs of fish which is 'overstocked' according to the rule, but they're all small fish with small bio-loads who live quite happily together. | |
| | |
January 23rd, 2009
|
| | Fish Keeper
| Which tank ?
Quote:
Originally Posted by dancerhas Great points everybody!
Here's how that formula would apply to our 4'' Chinese Algae Eaters:
2x(4x1/2x1/2) = 2 Gallons
Two 4-inch CAE's in a 2 gallon tank HA! In the case of long skinny fish, it's safer to go with one inch of length per gallon of water. This would bring us to 8. Much better, but not even close to what two CAE's need due to their bio-load and swimming habits. | Which tank do you have them in ? | |
| | |
January 23rd, 2009
|
| | Fish Bum
| I'm really glad that this topic has been opened. I find people are very quick to accuse others of overstocking (although they are often right!) without personal knowledge of the setup etc. Too many "1-inch-nazi's" out there! ;-) Stocking is a very dynamic thing, dependent on many variables, agree that is definitely a good base or guideline, which must be used synergistically with common sense, observation and experience (not that I have much of that last one myself!).  | |
| | |
January 23rd, 2009
|
| | Fish Bum
| Quote:
Originally Posted by pinkfloydpuffer When stocking... well, I usually have species tanks, so that makes it easy. But, if I were going for a community, I start with only a few fish. Then wait a while, add a few more. I keep an eye on the water quality. As long as the fish have the proper space, just watching the nitrates should tell you when you're fully stocked. With all of my tanks I can get away with water changes every other week (although I usually do it weekly anyways). For example, my 10g tank. If you look at it in my aquarium info in terms of fish it's quite overstocked. But, they all have sufficient room, and I never see nitrates over 10ppm, even if I let it go 2 weeks between water changes.
So, I say, forget the rule, figure it out through experience! |
Even though i am a noob, this does makes sense the most. | |
| | |
January 23rd, 2009
|
| | Moderator
| Quote:
Originally Posted by Dane I'm really glad that this topic has been opened. I find people are very quick to accuse others of overstocking (although they are often right!) without personal knowledge of the setup etc. Too many "1-inch-nazi's" out there! ;-) Stocking is a very dynamic thing, dependent on many variables, agree that is definitely a good base or guideline, which must be used synergistically with common sense, observation and experience (not that I have much of that last one myself!). | I will say that it is extremely rare to go over the one inch guideline and not have an overstocked tank. When we say that it doesn't work, we almost always mean in the other direction, i.e. a 10" oscar won't fit in a 10g tank. | |
| | |
January 23rd, 2009
|
| | Fish Keeper
| Quote:
Originally Posted by Drew 43920 Which tank do you have them in ? | 30 gallon. We do two weekly water changes to keep up with the bio-load. We bought them when we knew nothing about their potential size or proper stocking. They are going to be moved to a 55 gallon sometime...hopefully within the next month. | |
| | |
January 23rd, 2009
|
| | Fish Keeper
| Awesome fish..........
Quote:
Originally Posted by dancerhas 30 gallon. We do two weekly water changes to keep up with the bio-load. We bought them when we knew nothing about their potential size or proper stocking. They are going to be moved to a 55 gallon sometime...hopefully within the next month. | They are awesome fish........... | |
| | |
January 23rd, 2009
|
| | Fish Addict
| Mine is growing up in a community tank fast,  | |
| | |
January 23rd, 2009
|
| | Moderator
| Let's get Didgeridoo's thread back on topic. It's not about CAE's.
It's a discussion about One Inch Per Gallon Rule.
Thank you | |
| | |
January 23rd, 2009
|
| | Fish Master
| Well at least it wasn't me this time, Lucy! | |
| | |
January 23rd, 2009
|
| | Moderator
| Quote:
Originally Posted by pinkfloydpuffer Well at least it wasn't me this time, Lucy! |  Me either | |
| | |
January 23rd, 2009
|
| | Fish Keeper
| at the end of the day filtration plays a large role in stocking. good filtration results in good waste management. even with the largest of tanks if your filter is not up to speed it wont matter what you stock in it. | |
| | |
January 24th, 2009
|
| | Fish Bum
| I'm mainly interested in the rule as applied to neon tetras (or similarly sized schooling fish). It strikes me as off that a little tetra needs an entire 2 gallons to itself, but I'm not sure. That's initially why I thought this version of the rule seemed to make a bit more sense than the usual "1 gallon per inch (lengthwise) of fish" guideline. What is everyone's take on the 1 gallon rule as described in the original post in regards to tetras? | |
| | | | |
Similar Aquarium Fish Forum Threads 
