?? Fish to Gallon Ratio ??

I've been at my current tank for about 13 months now.

I'm always amazed however on the # of fish some people post are in there DT. As in 8 fish in a 30g tank- as an example.

I have used a ratio ever since I began, that I learned from what I felt to be a reputable source.

That Ratio being 1 fish per 10G of water.- MAX

What are your educated/experienced thoughts on this ratio?

Do I have to adjust, or is an acceptable ratio?

Disclaimer- My DT is having no problems, I now have 25 different types of coral, and a total of 10 fish, an urchin, Cleaner shrimp, CUC, etc.
It's a 125. I really don't want many, if any more fish, I'd just like to hear your acceptable ratio.

 

With saltwater, I think its just too hard to put a number too it. How big will the fish get at maturity? Whats its temperament? Whats it eat? Is it a predator? What filtration/LR do you have? What does it eat?

There are just way too many variables out there, IMO.

 

I've heard the 1" per gallon but with salt I feel that its just to difficult to say. I mean a tang in a 30 gal tank is just to small. At the rate that those little guys swim around it would be like you living in your bathroom with a refrigerator in it. I mean you have everything you need but it just doesn't make any sense.

 

Agreed simplifiying a stocking list to an inch/fish per gallon rule just doesn't work.IMO

 

There is no simple 'ratio' that will get you what you want in terms of stocking a SW aquarium.

It greatly depends on the determinants of behavior/aggressiveness; bio-load; how active the fish is (swimming space); the physical size of the adult fish; and dimensions of the aquarium itself (and sometimes diet, as Cosmo said).

 

No such ratio exists, you simply have to research the fish and take into account the other fish in the tank. with a ratio like what you posted it doesnt even take into account the fishes size, simply 1 fish per 10 gallons, this could mean 2 6 inch tangs in a 20 gallon tank. ive also heard people say 1 inch of fish per 5 gallons, but this also is faulty because you could either have an 8 inch trigger in a 40 gallon tank or 8, 1 inch cardinals in the tank, of course the cardinals would produce much less waste.

 

Agreed.
But for what it's worth... there is a calculator for it... don't recall what the math is on this:
3reef.com - Calculators

Ok.. just looked under the hood:

Code:

          $length = $_POST['length'];
                        $width = $_POST['width'];
                        $depth = $_POST['depth'];

                        //Cubic inches          
                        $inch3 = ($length * $width * $depth);
                        //Cubic feet
                        $feet3 = ($inch3 / 1728);
                        //Gallons
                        $gal = ($feet3 * '7.47');

                        if ($_POST['tank_type'] == 'fresh') {
                                $ammount = 1;
                                $type = "Freshwater";
                        } elseif ($_POST['tank_type'] == 'salt') {
                                //Insert the inch of fish for saltwater here.
                                $ammount = 4;
                                $type = "Saltwater";
                        }
                        $capacity = ($gal / $ammount);

                        $answer = "Your " .$type. " tank will most likely be at capacity with <strong>" .$capacity. " inches</strong> of fish.<br /><br />";

 

1" per gallon? So I could have 125 inches of fish? Don't think so.

Obviously, I'm not talking about whether the fish get along, that doesn't factor into the ratio at all. That's an individual thing like a few of you posted. MIne get along fine btw.

And size of the fish, yes, that's a factor obviously. For me, several of my smaller fish equals the mass of my Royal Blue tang, so yes, that's a factor.

The lfs where I started a few of my things, had this generalized ratio, in relation to waste export, fish health, etc. Obviously there is a wide range,

but as a general rule, 1 fish per 10 gallons of SW is a great rule of thumb to go by.
As in Rule of thumb, not all or none.

But I often see people posting how they have 8-10 fish in a 30g.- If they are all little strawberry basslets, it might get by, but small/medium fish?


** Thanks Matt for the calculator! This is what I came up with! Now, to make them all hold still and measure them! J/K

Your Saltwater tank will most likely be at capacity with 29.413125 inches of fish.


Aquarium CapacityWhat type of tank do you have?
Freshwater
Saltwater *
Tank Length 72 inches
Tank Width 18 inches
Tank Depth 21 inches

Thanks Matt, that is more reasonable, and takes into account size somewhat, even if it is overall length of the fish.
Good call

 

sure it is a fair guideline to go by, but hardly a rule of thumb. i would not give that as advice. matts calculator is very accurate, i cant say i have ever seen it before now.

the person that mentioned 1 inch per fish per gallon was saying that the rule was incorrect, no reason to be unkind.

 

Its a general rule I didn't say its the law! What if you had nothing but non-aggressive fish? Besides haven't you seen your lfs have several fish in their display tanks to where they are close to 2" to 4" of fish per gallon?

I'm not saying go out and put 200 fish in a 30 gallon tank I am stating that you need to do your research before you put your fish in to your tank.