Inch per gallon?

[Hookman]

what do you guys use for stocking? I work at petco and they told me one inch per two gallons. I thought it was three inches per gallon. Any ideas, I just forgot because I have had an established tank for a while and haven'r had to use this info in a while.

[Leader of Men]

Some Freshwater people live and die by one inch per gallon. Truth be told there's no formula that will work.

But I've often heard saltwater is 2 gallons to every inch of fish.

[Kurt_Nelson]

Saltwater and freshwater rules are different. Rules are not good because 4" of clownfish is an entirely different bioload than 4" of puffer.

With that said though, you'll find different people giving different rules, but they all are between 1" fish per 2 gallons and 1" fish per 5 gallons. It will all really depend on your total filtration. I would never recommend 1" per 2 gallons to someone though. That's just a LOT of fish.

[amkelly]

the inch per gallon rule is completely bogus. the real deal is having enough space for your tank mates to have room for themselves and to live happily with others.. for example in a 30 gallon tank you might put a goby and 2 clownfish. and maybe a psuedochromis. this most certainly isnt thirty inches but it probably would be the max amount of fish i would put in a 30. the point is that all fish need their own space. dont think they are going to stick to the four inches they are in, they want to swim and be free to swim

[melosu58]

I agree. It all depends on the fish and their needs.

[Kurt_Nelson]

Originally Posted by amkelly

the inch per gallon rule is completely bogus. the real deal is having enough space for your tank mates to have room for themselves and to live happily with others.. for example in a 30 gallon tank you might put a goby and 2 clownfish. and maybe a psuedochromis. this most certainly isnt thirty inches but it probably would be the max amount of fish i would put in a 30. the point is that all fish need their own space. dont think they are going to stick to the four inches they are in, they want to swim and be free to swim

Agree kinda... but no one is saying 1"/1 gallon is the rule. If you go with the 1"/5 gallon "rule", then that 30g tank should be able to hold 6" of fish... which is about 2 clownfish. If you go with 1"/3 gallons, then it's 10" fish which is about where your suggested stocking level is at.

I agree that the "inch/gallon" rule for stocking has a lot of assumptions built into it and doesn't distinguish between "fat" fish and "skinny" ones - but at least it's a start for people when they're getting into the hobby. It would at least keep people from stocking their 55g with 8 tangs wondering why they're having water quality issues!

[lando]

take the "inch per gal." rule and throw it out the window. I agree with the others in that it is a VERY poor measure for stocking. You must first find the appropriate biological filtration needed for a tank (be it reef or FOWLR) then slowly build a stocking list around that. Some fish require larger tanks, while some do fine in smaller tanks. The point being...there is no "rule". Pick the appropriate fish for the size of tank it is going in and ensure enough biological filtration.

[Kurt_Nelson]

Originally Posted by lando

take the "inch per gal." rule and throw it out the window. I agree with the others in that it is a VERY poor measure for stocking. ...

OK... so how do you suggest a new person make a stocking plan? We preach "add the more docile fish first, then work your way more aggressive" which implies you have your entire list figured out to start with. (Which is a good idea, by the way.)

So how do you plan that list if you only know the tank size requirement for each fish? If you have 1.5 lbs/rock per gallon (another poor rule probably, but it's a start), just how do you know how much filtration that is? Is the amount of fish you can support one less than you had before your tank crashed? (I read that one somewhere and kinda liked it!)

I agree... it is a poor rule. But it's a starting point. Or is there a better starting point for people starting out?

I've helped teach people things where there's more than one way to do something and in reality there really aren't set rules on how to do things. There's always exceptions. But doing it the wrong way could get you killed. So you teach them one way, and one way only. That gives them the basic skills to progress without killing themselves. Only later do you teach them the other ways and then explain the pros/cons of the different ways. At that point, they have some experience under their belts to comprehend and make informed decisions. But when they're just starting out, that experience has yet to materialize and even if you did teach them the different ways it wouldn't make sense to them. I kind of see this as something like that.

[Innovator]

The inch/gallon rule and all other measurement/housing rules are outdated. It does not make reference to an animals girth, territorial attributes, or locomotion. A basic example would be, if a one inch/gallon rule was in effect, then a 10" fish would be properly housed in a 10g tank. False.

There are plenty of resources that enable people to research their fishes needs other than aquarium size, a very important site such as fishbase.org.

[Kurt_Nelson]

That's a great database, but I'll ask the question again...

How do you give a new saltwater person a place to start with understanding how much fish their tank will be able to hold?

I'm not trying to be a jerk here, but just saying "the XX inch/gallon rule is junk" doesn't help anyone. (And note that nowhere here, anyone is saying the "rule" is 1 inch/1 gallon.) What advice do we give people, other than "post your proposed stocking list and we'll critique it?" Seems like folks at least need to start with some type of crutch - along with the disclaimer that there's other things that factor into the equation like minimum tank size, etc.

[Innovator]

A valid question Kurt and I wish we had an "easy button" to depress. As some of us experienced aquarists know, there are very few hard rules in this industry. No one may be stating any particular rules, but "inch/gallon" was brought up and is common mythinformation. How do any of us begin to understand what can and cannot be done? Well, we research. This may be a very generic answer, but databases, publications, and scientific 'works' are available that provide free information on fish specie representations. To a certain extent, much is guesswork in that you are forcing an animal to "behave normally" in an un-natural environment where variables are constantly being tested i.e. territory, predator vs. prey, locomotion, food, growth, aquaculture vs. ornamental, etc.

I know I am seemingly floating around the answer and probably because there is no easy answer. IME, the aquarist must educate themselves on the dynamics behind their system(s) and understand that specie behaviors play an intricate role in an "expected" outcome.

In a nutshell, it would be best to point a new aquarist in the right directions for self-knowledge and answer questions to a greater extent (medical implications as well) rather than simplified means such as minimum size differentials.

[Kurt_Nelson]

We're really all saying the same thing. I just guess I'm not seeing the harm in giving a stocking "range" along with several caveats. (Make sure the minimum tank size for the fish is maintained, don't stock the same species unless mated pairs or you understand the risks of trying to mate them, take into account how the fish feeds (messy?clean?), etc.)

When I look back on my original "plan" for my 46g, I laugh at how many fish I had planned for in there. They were all size-appropriate for a 46g, but there were just too many. Then I started researching and ran across the variations of the "rules". After popping my eyes back in my head, I whittled down my list to a more reasonable goal. And as continual education goes, it got whittled down yet again as I started to stock my tank. I now have 3 chromis, 1 clown, 1 bangaii cardinal, and 1 y.clown goby in my tank. (About 2.5"/gal of full grown fish, if you're counting.) Even with an oversized skimmer and plenty of live rock, I think my tank is probably one fish over its capacity but will deal with it. I can't fathom the problems I would've had if I'd of tried to carry out my original (or even #2) stocking plan.

You're right though - "rules" that really aren't rules pervade all hobbies, industry... you name it. I think of the "rules" I use to do my job, and realize that only after having maybe 10 years experience do you understand when it's OK to break those "rules" or where the rules don't apply. Back in our hobby, look at the tank turnover rule: 10-20x your tank size, in gallons per hour... right? Well... after having MaxiJets and then switching to Koralias, I can tell you that 200gph out of a MaxiJet is NOT the same as 200gph out of a Koralia. We're using FLOW as a "rule" where we really should be using the water VELOCITY because that's what's really important. But should we throw out that rule? Personally, I'll still use it because it gives someone a reference - a good starting point - to explore what will work in their tank.

OK... I feel like I'm beating a dead horse, so I'll just sit on my hands now!

[cmor1701d]

Kurt you brought up a very valid point. I think we all have had hopes of schools of fish in our tanks. Those smart enough to listen to the folks who made that mistake years ago are still in this hobby. I know I go throug periods where I don't to tank maintenance as often as I should, or overfeed, so overskimming, lots of LR and a large volume of water have saved me. I consider my 125 fully stocked with my 9 fish, but so far it works and everyone is happy.
7" Sailfin tang
7" Foxface lo
4" Blue tang
3" A. percula
2" A. percula
4" Coral Beauty
3" Pajama cardinals (pair)
3" Green Mandarin
I miss my bi-color blenny, maybe I can add 1 more....
But I also miss my royal gramma

[Dennis210]

Bioloads are dependant upon the type of system one is running. In salt systems with decreased oxygen levels try for a more realistic rule of 1 fish for every 10 gallons. Fish are small at first but they Grow! Also in most salt tanks there is more than fish contributing to the overall bioload! I see many folks overstocking and overfeeding and quoting inch per gallon statistics. I get calls to fix those systems alot! Read read read. Look for books with publication dates 2000 or newer. Also look at newerskimmer designs. You get what you pay for. I can tell ya Seaclones, Skilters, and Prizms are all junk!