Experts such as MM and Ghapy, please come here. Need your help...?

Question

Do you think the 1 inch of fish per gallon rule is accurate?

If no, what "rule" would you consider accurate?


thanks

I know, they did delete my question before.

Though, I did write, "such as".

Answer 1

I'm also not MM or Ghapy, but here are my thoughts on the matter.

The "inch of fish per gallon" is a simple guideline, but doesn't take into account body shape - fish with wide or deep bodies produce more wastes than fish with thin, slender bodies. Another guideline uses grams of fish per liter of water - this will take body shape into consideration because a "wider" or "taller" fish will have more weight from the additional body mass (but have you ever tried to weigh a fish?). There's also an inches of fish (okay, we already know the problem here) per surface area - multiply the length and width of your tank and divide this number by 12 for the "inches" of fish to keep - this is the only method that takes into consideration the shape of the tank and the O2/CO2 exchange. None of the methods considers space needs based on activity level or the territoriality/aggressivness of the individual species either. Also, some species have preferences for the area they occupy in the tank - the bottom fish, midwater, and surface species.

The "guidelines" as I've given them above will apply to typical, freshwater species only. Some species should only be kept one, or a mated pair to any sized tank, others should have more room if sensitive to environmental conditions because a larger tank will keep temperature and chemistry more consistent. And then there's saltwater.

None of these methods will mean anything if you overfeed or don't perform water changes and cleaning on a regular basis. You can get away with higher stocking rates with larger filters and/or using a sump (hidden tank plumbed to your fish tank to increase your overall water volume (this is what fish stores use, which is why they look overstocked, plus they usually have an automatic water replacement system that changes a set volume per hour) Maybe the best thing to do is calculate using several methods and take an average, or consider your committment and experience in fishkeeping (or lack thereof) and keep the stocking at the lower end of the range - this would be the safest method.

So I'd have to say no single method is completely accurate - it's best to consider all these factors and arrive at your own realistic stocking rate. If in doubt, understock. I don't know of many problems that arise from having too FEW fish, as long as you have an adequate number for the species that prefer to be in schools.

I've also come across a few "aquarium planners" that attempt to take all these other factors into consideration when stocking a new tank. Here are links to two of them:
http://www.tropicalresources.net/phpBB2/templates/BMan1Blue/Stocking.htm
http://www.thinkfish.co.uk/community.html
You input the info, and it will sort through what you have (or plan to get) and point out potential problems.

ADDITION: What Jon said is true - I think you asked this a few days ago and the question was pulled. Or there was at least a similar question and I was in the process of writing an answer when the question "disappeared". When you ask for a user by name, it looks like a personal communication which is against the community guidelines, even when it's a legitimate question.

Answer 2

There is no steadfast rule, but this may help...

Common Glass Aquarium Sizes

5.5 Gallon 16x8x10 (128 sq. in.)
10 Leader 20x10x12 (200 sq. in.)
10 Hexagon 14x12x18 (127 sq. in)
15 Gallon 24x12x12 (288 sq. in.)
20 High 24x12x16 (288 sq. in.)
20 Long 30x12x12 (360 sq. in.)
25 Gallon 24x12x20 (288 sq. in.)
29 Gallon 30x12x18 (360 sq. in.)
30 Gallon 36x12x16 (432 sq. in.)
30 Breeder 36x18x12 (648 sq. in.)
33 Long 48x13x12 (624 sq. in.)
37 Gallon 30x12x22 (360 sq. in.)
38 Gallon 36x12x20 (432 sq. in.)
40 Long 48x13x16 (624 sq. in.)
40 Breeder 36x18x16 (648 sq. in.)
45 Gallon 36x12x24 (432 sq. in.)
50 Gallon 36x18x18 (648 sq. in.)
55 Gallon 48x13x20 (624 sq. in.)
65 Gallon 36x18x24 (648 sq. in.)
Petite body fish
1” per gallon or 1” per 12 sq. in. of surface
For example 20 long has 360 sq. in. surface area
360/12=30
Can a 20 long support 30” of fish? Probably not.
A 20 high has only 288 sq. in. surface area
288/12=24
Can a 20 high support 24” of fish? Probably not.
A 25 is also 288 sq. in. surface area
288/12=24
Can a 25 support 24” of fish? Probably.
I like to average the two for a more accurate capacity.
For the 20 long, 30 by surface area, 20 by volume averages to 25”
Can a 20 long support 25” of fish? Probably.
For the 20 high, 24 by surface area, 20 by volume averages to 22”
Can a 20 high support 22” of fish? Probably.
Why does the 20 long support 3” more fish that the 20 high?
A larger surface area allows a greater oxygen exchange, which is as important as volume of water.
Large bodied fish, such as gold fish you need to double or even triple these numbers, i.e. 3 gallons per inch and 36 sq. in. of surface per 1” of fish.
This is not the only consideration for fish tanks. Types of fish will appreciate one type of tank over another. For example, fast swimmers like Zebra Danios, Pearl Danios and Blue Danios will do best in a tank that is at least 30” long. They would be better kept in a 20 long rather than a 25. Giant Danios would do best in a tank at least 48” long. They would be better kept in a 55 rather than a 65.
On the other hand, slow, tall bodied fish like Angel Fish and Discus will do best in a deep tank. They would be better kept in a 65 rather than a 55. They, like other cichlids also need a bit more than the 1” per gallon and/or 12 sq. in. surface.

Answer 3

I believe the rule is only a guide line to follow. There are plenty of extenuating circumstances that need to be factored in. Such as I have a lionfish, they typically grow to about 18 inches, therefore by the rule I could house him in a 20gallon tank. No way can you do that. I currently have him in a 55 gallon and that would be the smallest anyone should go.

Answer 4

No it is not accurate. I have seen yahoo delete posts of this nature specifically asking for individuals as well, just to give you a heads up. You can email those members direct as I have mailed MM many times. You could apply the one inch of fish rule to smaller less waste producing fish, but you can't for example safely keep a 6 inch oscar in a 20 gallon tank just because of the sheer waste they produce. You also have to account for filtration. In cases as above, if you have more then enough filtration present, you may be able to work around the size, but you also bring into play long term health effects of a fish not housed in a tank needed for it's breed and size.

Answer 5

The rule is as something says, its 1in of fish to 12sq inch's of water surface area. its not 1in per gallon or 1in per 12cube inches, its 1 inch per 12sq in of surface area.
the only way you can increase the amount of fish per your tank is to increase the surface area by fitting a sump filter which is just another tank below used as a filter.
you can filter your water internally externally you can do 200 times an hour, or add bubble walls till there's more bubbles than water however, when you've finished its still 1 in per 12sq in of surface area.