1" Per Gallon Rule

[ian]

just wondered where everyone stands when it comes to the 1" rule when it comes to smaller tetra, rasboras etc. I'm thinking of getting another shoal for my tank, i already have 10 Rummys. I was thinking of 10 Harlequins, how do you work out the 1" rule with these smaller fish?

 

[Truck]

Never used it, I think it's a load of rubbish and it will never work.

a 2 inch fish is 8 time bigger in volume than a 1 inch fish of the same shape, so surely it produces 8x as much waste, When I stock my tank I put what I want in it with regards to numbers, I had 25 neon tetras a pair of rams and 2 BN plecs in a 60 litre once, and it wasn't over stocked, anyone can tell me it was, but I know it wasn't.

 

[Ben M]

i agree, i have been told many times that my tank is overstocked, but the water parameters are fine, and the fish are all ok, so i don't see the problem.

cheers

 

[AdAndrews]

I too think its rubbish, not just what truck said, but, all set-ups need to be judged individually, some that have better filtration will be able to cope with higher bioloads, plus, enviroments in nature where that particular fish species is kept may be fairly "crampted" in a small space anyway, so, its a useless saying.

 

[fatheadminnow]

I think it is a fairly alright idea for the absolute beginner, and until that person can figure out what is going on, they should be okay. After that, once that person gets his or her head around what is going on, and how much a particular fish produces this much ammonia (their bio-load), then they can re-work their stock.

Of course, if that person comes on here and asks for advice on stocking, we are going to put the rule aside and give him or her advice on what we know.

Other than that, I think a tank should be stocked with respect to how much a fishes bio-load is, and so forth in relation to filtration what not, not really their body size.

-FHM

 

[GAB99]

isnt the rule that is circulated around the net and the world only a part of the full rule?

i heard its 1 inch of adult, linear fish that doesnt exceed 3-5" in total lenght per gallon.

which excludes oscars,chunky fish, gold fish, and so forth until we are left with the majority of tetras and barbs and whatever im missing.

i think the full rule would be excellent for the begginer as to what mr 130 is saying.

 

[ian]

thinking about it, like what Mojo says, the majority of fish we are left with are the ones with the lowest bioloads, which really make the 1" rule useless!?.

 

[kelly528]

I think it requires some eyeballing but it is a relatively good jumping off point.

I will have to check when I get home, but I have a book where they actually tweak it and say 1" per gallon for fish under a certain size, 2" per gallon for bigger fish and 3" per gallon for bigger fish, etc, etc, etc.

Yet others interpret it as 1 cubic inch per gallon. For example

1 neon = 2" length x .5" across x .5" height, which equals 2 neons per gallon.​

 

[GAB99]

as kelly has put forth, it seems that there will ALWAYS be variations to this rule, but i think we can all aggree that its mostly for the slim little fish that stay little.

and i hate to see that the shortest and least descriptive of these variations is in mainstream circulation at the moment.

 

[roadmaster]

I agree that the one inch per gallon rule needs to die a quick death. But feel for the novice or beginner,It is a guideline that will serve them until as mentioned,they understand that more fish=more waste=more load on biofilter=more organics in the form of nitrAtes. Add to this the habit of feeding extra for numerous fishes,and water quality can quickly begin to deteriorate.
There will ALWAYS be those that proclaim,"I kept/keep ,X amount of fish in this or that size tank with no problems just as there are those who insist on keeping goldfish and Bettas in bowls.
In my mind, it's not about how many fish can I fit in my aquarium. Anyone can do this with frequent water changes and over filtering the tank although if fish don't share similar requirements,they seldom thrive,they just struggle to survive. I like a tank where fish have plenty of room to explore the enviornment I have attempted to create. They are not stressed,harrassed,attacked,or crowded ,and water quality is easily maintained between weekly maint.All of the fish are compatible,they share similar requirements with respect to pH,GH,KH and temperatures.
This in my view is caring for tropical fish.Opinions Vary.

 

[fluvial]

Well said Road Master -
I totally agree !

 

[Inchworm]

It's not a rule and can never be one. To make a decision on whether or not a tank is fully stock requires observation of the fish's behavior and water tests, especially tests for nitrates. Since the amount of nitrates naturally in the water supply varies from place to place, everyone does not start out equal and so one rule cannot apply to all.

In most cases, however, the inch per gallon (with small fish) guide is a safe bet to start out with. Beyond that, it's up to the individual to evaluate their own ultimate stocking situation once their tank is cycled and their existing fish are settled in.

 

[OldMan47]

I always start out with new fish trying the inch per gallon guidance. Most of the fish that I keep are small ones with a light bioload so it works for me. Once the tank is set up and functioning, I judge the bioload by seeing how long I can go between large water changes and how much water I must change to keep things right. In reality, almost any number of fish can be kept in almost any amount of water if you are willing to do enough water changes each day. The reality for me is that I don't like to do large and frequent water changes so I limit the number of fish to small numbers that won't push my nitrates out of control quickly and really maintain my stocking levels at a point that a filter failure will not kill off the fish in the tank during the first day or two. As Inchy says, you do learn to judge stocking levels by observing the tank but I still like to start out light as the inch per gallon guidance would dictate.