1" / Gal

[Fishy_7]

The 1" per gallon rule, does that relate to the amount of space available to the fish within the tank OR the filtration of a filter for the tank?

Thanks.

 

[Miss Wiggle]

i think it's a combination of a number of factors not just any one thing, it's really a sensible guide for how many 'normal community tropicals' you can fit into a tank assuming everything is normal and nothing is upgraded, it also gives enough leeway in your stocking for the odd newbie error like overfeeding or missing a water change etc

the 'avergage' filtration based on filter manufacturers recommendations for the size tank they can filter
the amount of swimming space for the fish
average amount of maintenance
average waste producing fish
avergae amount of oxygen in the water

 

[Tokis-Phoenix]

The one inch of fish per gal rule is basically only a rule of thumb and shouldn't be completely followed as it does not take so many important factors into consideration when stocking fish. Its basically there to help people decide what might go in their tanks and what definately might not go when stocking their tanks, the rule mostly applies to small peaceful community fish.

 

[OohFeeshy]

'normal community tropicals'

But how many fish really do fit into that category? Very few, when you think about it.

 

[PoPoV]

'normal community tropicals'

But how many fish really do fit into that category? Very few, when you think about it.

Very true. In no way does this "rule" mean that you can put a 8" Oscar in a 10gal tank because it fits the inch per gal rule.

 

[rdd1952]

The main thing with the 1" per gallon guide is that if you use it for any fish other than the messy ones like goldfish, plecos and oscars (not reallly a community fish anyway) you should never be overstocked. Will you be fully stocked, probably not. The main purpose of it is to help newbies keep things under control.

 

[Don Trinko]

If you go to the library and check out an old Tropical fish book you will find that they calculated the surface area of the tank and then you allowed small fish somany sq inches of surface area ( I think it was 10 sq ") and bigger fish more area per inch. ( I think it was 50 sq " per inch with chicklids) If you had an air stone you could double that, If you had an air stone and a filter you could tripple it! I used these rules many years ago and they more or less worked in that my fish stayed healthy and lived a long time. The only thing we ever tested was PH and hardness.
Things have improved in many ways but in some ways they are worse. I had Angel fish back than and no one ever heard of "angel fish disease". When you bought fish at the LFS it was assumed they were disease free. Now almost all of the diseases and deaths come within a week of when I buy the fish.
Don T.

 

[Danno]

I personally don't go by the one inch per gallon rule at all. Their are too many varying factors. When making a tank with common tropicals I go one inch per fish per 3 gallons. One inch per fish per gallon is crowded for me.

 

[Tolak]

The one inch per gallon guideline is just that; a guideline. It's an old theory, designed to keep newer aquarists from overstocking or getting in over their head. Everyone quotes parts & pieces of this guideline, which leads to confusion.

One inch of slim bodied fish, with an adult length of no more than three inches, per gallon of water.

 

[smooth_bourbon]

One more thing is what level of the aquarium the fish is going to dwell in. 1 inch per gallon with all bottom dwellers could get pretty crowded, especially in a tall tank.

 

[Bignose]

The one inch per gallon guideline is ... designed to keep newer aquarists from overstocking or getting in over their head.

This is the key phrase in the entire thread. No one with any significant experience follows the rule religiously, but the rule is exceptionally handy for beginners. Many, mnay beginners start up with a tank that has in the order of 60 to 100 inches of fish in usually something around a 10 gallon tank. It doesn't matter what kind of fish they are, that tank is overstocked. So, the 1 inch per gallon rule is very easy to remember and easy to apply and is a very good starting point in the vast majority of cases when the forum members chime in about that beginner's tank. And it is a good guidleine to keep in mind when that beginner sorts everything out. Again, there are a lot of variables that determine the actual possible stocking of a tank, but for beginners one inch per gallon is pretty darn good as a starting point.

 

[Ristof]

I have used a different method that may be right or may be wrong but we don't have gallons here in Aus, we have litres

When I first started I would measure the front of the tank and then lets say your tank was 24" long then you could put in 24 1" fish. 12 2" fish and so on.
The only thing you had to remember with this was the size the fish would grow to more then the size it was when you brough it but then again with any rule

I know depths and widths are different on tank but then again it is just a guideline. Do you feel more confortable in a 1 bedroom flat with 10 people or a 2 bedroom flat with 4 people. I know measuring is different but princible is the same

 

[Miss Wiggle]

'normal community tropicals'

But how many fish really do fit into that category? Very few, when you think about it.

i'd disagree, as others have said this really applies for beginners, walk into a bread and butter lfs what will you see?

tetras, rasboras, danio's, gourami's, cories, otto's, platys, mollies, swordies, guppies etc etc....... all these fish 'work' on the " per gallon rule

 

[andywg]

Oooo.

I just did a quick rough tally on my large tank and I don't think I make it under 2" per gallon, let alone 1.

As mentioned above, the 1" per gallon is purely as a guide for beginners when buying the sort of fish most beginners buy. It allows for inadequate filtration, waste building up in the substrate, infrequent water changes and overfeeding.

If you are keeping a strict maintenance routine with extra surface agitation and a large filter and water changes then you can easily push to 2" per gallon, especially if you aren't stocking foot long monsters.

This is one of the reasons I like the salty side so much, there is no guideline and everyone is told to evaluate what the fish needs and how the fish will fit in to the current (and future) stock.

 

[loachman]

The other point is the inch per gallon is by far the easiest stocking method. Fish are almost always sold with some indication of their adult size (in inches) and tanks are sold by the gallon. It is very easy to do the math and figure it out with knowledge that should be right in front of you.

The other methods, like surface area per fish, stocking by aggressiveness and other factors, etc. require alot more knowledge and research. They're not beginner friendly methods like 1" per gallon (although some aren't all that difficult).