# 1 gallon per inch of fish rule



## tmshck122 (Oct 4, 2012)

I have heard from pretty much everyone that you need atleast 1 gallon per inch of fish that you have. So by that logic, I can put 1 Bala shark in a 29 gallon tank for its entire life then correct? Even if it grows to be 16" long


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## Redbug (Sep 10, 2012)

I don't think so. It would be cruel. I understand that the 1"/gal rule is a very rough guide
for stocking your tank. The fish might live but I don't think it would be happy. Google
each fishes needs as they all vary. Good luck.


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## jbrown5217 (Nov 9, 2011)

That rule works for fish like neon tetras. Slender fish that don't get bigger than 2". #1 bala sharks need to be in schools of at least three if I remember correctly. So that 16" quickly turns into 48" anyway.


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## navigator black (Jan 3, 2012)

The one gallon per inch rule is a weak attempt at measuring bioload, originally conceived for fish under two inches in total length. It's for tetras, Danios and killies - fish that are torpedo shaped. It isn't sensible to measure a fish from snout to tail and not from belly to back - one inch of goldfish is several inches of neon or zebra, bulkwise.

Fish move. A restless species like bala sharks call for a different calculation - a behavioral one. I'd suggest the minimum ten inches of front glass per inch of fish, by which a 16 inch Bala Barb would need at least 160 inches of front glass, as an absolute bare minimum. A 29 is at most 36 inches, so it falls a wee bit short of adequate.

There is no logic to the one inch rule. It is a leftover from another era, when pre-silicone tanks were small and there was no question of keeping of large, fast or bulky bodied fish.


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## ImBrovvn (Oct 10, 2012)

I think a 29 gal for a bala shark might be considered animal cruelty
Lol


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## navigator black (Jan 3, 2012)

It wouldn't be intentional animal cruelty in most cases. People ask stores for advice on fish in all sincerity, but the answers they get are often sincerely misinformed. I'll wager 90% of chain store employees don't know how large a Bala can get, or anything about its needs. The same for Oscars, pacus or Dempsies - the pet trade works on the assumption they will die from crowding long before they become a problem for the buyer.

If the welfare of the fish had any value, chain stores wouldn't carry any of the above fish. They'd have to be special ordered. But large fish produce enormous spawns, and that makes them very very cheap wholesale. In a good sized tank, they can be very easy to breed, especially if you use a syringe (yup) to inject hormones into a fish (easy with big fish). That's how they often spawn Balas on the fishfarms..


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## majerah1 (Oct 29, 2010)

I wish that rule would be thrown out, its not accurate for most of the fishes we keep.


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## coralbandit (Jul 29, 2012)

I think a safer method would be to use surface area in some formula.I understand the front glass with cichlids and think whether completely accurate it is easier for people to understand. Surface area takes away the notion that more gallons equall more space since most tanks only increase their volume by getting taller.The tanks people keep should be shaped like the fish they keep; tall tanks for tall fish(angels/discus) and long tanks for long(torpedo shaped fish).This breifly fits the living space to the behavior the fish have.The tank you have(shape and size)is more important than many think.


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## Auban (Aug 8, 2010)

the one inch per gallon rule is actually quite old. less than 60 years after the first person said "aquarium" in connection with fish (Philip Henry Gosse), the 1 inch rule was layed out in a book,

"Goldfish Breeds and Other Aquarium Fishes, Their Care and Propagation..."
By Herman Theodore Wolf *1908* 
im sure there is earlier mention of the one inch per gallon rule, but i havent read it yet.

there are still several such rules and statements lingering around from the very earliest years of the hobby. i imagine it is because such prestigious men made the "rules".

take Dr Phillip Henry Gosse for example. for years and years, everything he said(or wrote) was taken as gospel. (_if you dont know who he is, your probably not a reefer_.) 

im sure this "rule" will be ebbing back and forth for years.

the aquarium hobby is like that... sometimes it just doesnt make sense. we consider reef tanks to be complicated, but thats actually where the hobby got started. back in 1854, Dr Gosse was making his own synthetic seawater... 

i have a feeling that unless a more simple way of explaining stocking guidelines to someone new to the hobby shows up, we will be stuck trying to educate everyone who recieve advice from the local pet store "one inchers".


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## navigator black (Jan 3, 2012)

I wasn't aware that Gosse was behind that rule - interesting.

The one inch rule will last because it tells us what we want to hear. It says we can have buckets of fish in small tanks. Almost every aquarist wants more fish than he or she can have, and one inch per gallon gives you that, in colour. Humans love rules that allow them to indulge themselves - and in aquarium terms, the one inch per gallon myth may kill fish, but it also sells them like crazy.


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## majerah1 (Oct 29, 2010)

Nav, when you say it like that, it sounds like we have an animal hoarding problem, lol. 

I had no idea the rule was such an old one. Love learning new things about the hobby!


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## ImBrovvn (Oct 10, 2012)

Sadly, the big pet stores will probably never stop telling people bout the 1 inch rule. All just to make a buck.


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## navigator black (Jan 3, 2012)

When I was younger, I had one 33 gallon tank. My local store informed me it would hold 44 tetras. Why 44 tetras I'll never know, but I chose to believe that. Hey, I had known the owner for years and I loved keeping tetras in groups of 4-6. With 44, I could have a lot of groups.
And so, I kept a lot of tetra species, convinced they were short lived and much smaller than they needed to be. My pet store friend kept selling me replacements, and always let me know in advance if he was getting a new species.
I started buying aquarium magazines, and quietly and politely figured out why I had small, short-lived tetras. When I think back on it, those tanks must have looked like commuter train stations at rush hour, 24/7.
My friend went bankrupt and I found better stores, and I learned that the things we take on faith would be much better researched, questioned and analyzed. I think with experience, we aren't likely to buy into one inch per gallon rules, but rather to define our own stocking rules depending on the our knowledge of the fish we want to learn about and enjoy. 
But I also know there are a lot of people in the boat I was in, looking for convenient formulas based on nothing...


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## Auban (Aug 8, 2010)

what i find interesting is that many fish stores still use the guidelines laid out for goldfish(of all fish) way back in the late 19th century. books such as "rustic adornments for the home of taste"1895, by Shirly Hibberd, actually suggested even more ridiculous stocking guidelines of half a dozen 4-6in goldfish for a single 24 gallon tank, or no more than four medium fish of 2-4 inches in a planted one gallon fish bowl. remember, there were no filters, air pumps, or even artificial lighting back then, and water changes were discouraged unless your fish started to die. 

i havent been able to pinpoint exactly where this misunderstanding came from, but it didnt come from Gosse. between 1848-1852, Dr Gosse and Robert Warrington conducted a series of experiments in order to develop a "balanced" aquarium. 
it was then that they learned of the benefit of snails. what they actually said about stocking was that a fish, around 2-3 inches long, should have no less than three gallons to itself, and any larger or more delicate fish should have far more. they also advocated dense planting, several snails, and one tadpole per fish.

something i find really interesting is that most of the early authors of aquarium books strongly opposed fish bowls. they generaly agreed(even Shirly Hibberd) that a fish bowl was generally a cruel fate for a fish. 

i would be surprised if any of the gold fish today could withstand those conditions for long. way back then, not only did they often live for extended periods of time, but there were several successful breeders that kept their goldfish in conditions we wouldnt see fit for a betta today. i think that the success back then stemmed from the fish being bred. it was probably only the slowest growing and most stunted lines of gold fish that managed to survive long enough to breed. as we got better equipment, we could keep less "hardy" lines alive, producing fish that couldnt survive such conditions.

to bring this back on topic, it seems the one inch per gallon rule actually worked for some people way back then. some people were actually able to keep fish for years and years in incredibly small amounts of water, without doing water changes. that doesnt mean that we should do the same thing today... the rule was in reference to goldfish, which were presumably a bit less delicate, slower growing, and far more stunted back then than they are today. as a fish that was bred indoors in pots and such for hundreds and hundreds of years in china and japan, it would have actually been a very good candidate for such a tank. the one inch rule worked for them because that is how many, if not all of the lines were developed. 
one reference i found stated a small fish as being 1 inch, a medium as 2-3 inch, and a large fish as 6 inches, with the occasional giant of up to 8 inches, when grown in a pond.
today, a 6-8 inch gold fish isnt all that spectacular, even when grown in a fish tank...

anyway, i think i have rambled on too long. this is one of those topics that interest me. i love reading old books and comparing what they contain to the information i find available today and trying to explain the discrepancies. sometimes it seems to go beyond a simple lack or gain of understanding. the one inch rule may have worked for a fish that was bred for it, and yet it would still make sense that it would never work today.


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## Hooperman42 (Oct 23, 2011)

Agree I always thought that "rule" was nonsense. It is about bio load. But that does not mean that hiding places, amount of substrate and amount of real swimming room do not come into play. For example a fish that likes to cruise in schools across the tank is not going to be happy without his buddies and they will not enjoy navigating around decorations big plants or other "obstructions"
Like other fish. I think it is important to take the advice above about researching each fish type and their preference in living conditions, hiding places, lighting, temp etc. :fish-in-a-bag: < see he is smiling but miserable.


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## coralbandit (Jul 29, 2012)

he is smiling isn't he? VERY NICE!


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