# of Fish vs. Tank Aqaarium Size

[Gman44]

Hello,

What is the basic Rules to follow when purchasing the number of fish vs. to the tank you will house them in?

I know there a few factors in the formula.

Like types of Fish & how many? x Also how large they can grow? = size of tank?

for example 20 Goldfish x 6" each = ?g

Please do educate me.

thanks.

[Neesmo]

http://aqadvisor.com/AqAdvisor.php?AqVolUnit=gUS&AqTempUnit=F&AqLengthUnit=inch

[syno321]

The activity level of the fish is at least as important as size. A 6" active fish like a Pictus Catfish would require far more tank room than a Loricarid of the same length.

[BettaFishMommy]

as well, you have to consider the bioload that the fish puts out. different species of fish of the same size may not necessarily create the same amount of waste.

[Jayba]

I have heard a lot of people say 1 inch of fish per gallon, this means their adult length. For example a 1 1/2 inch cichliid that grows to 4 inches gets 4 gallons of tank.

[punman]

My 90 gallon has twenty 4 inch tropheus and that is about as many as I would want in there. Yet I am sure I could put forty skinny 4 inch cyprichomis in the same size tank.

On a short term basis I can have forty half inch fry in a ten gallon tank. That works out to 20 inches of fish in 10 gallons or 2 inches of fish per gallon with no problems. On the other hand, one 5 inch frontosa in a 10 gallon is a half inch of fish per gallon and that would be a disaster (and cruel).

Many people consider fish size and filtering levels when deciding but some do not consider the compatibility issue. As I mentioned my 90 gallon has twenty 4 inch tropheus with good health of the fish and little waste accumulating and I do one-third water changes every 10 days. Instead, imagine if I had two Jack Dempseys, two tropheus, two demasoni, two Blue Dolphins, two electric blues, two discus, and so on, up to 20 four inch fish. The fish inches per gallon would be the same, the tank could handle the filtering, the water conditions would be fine, but fish would die, get picked on, and be unhealthy.

Some of the fish forums do a good job of specifying how many of a certain fish should be kept in a given size tank. Cichlid-forum does a good job in their library of cichlids. I say err on the side of caution. When the recommended is a 75 gallon tank for certain species of fish some say they will try it in a 55. I say go with the 75 or safer still, use a 90.

Edited March 6, 2010 by punman

[darkangel]

Back in the day when dinosaurs roamed the earth, the basic rule was 1 inch of fish per gal or 4 inches of fish per square foot of surface area. However this was for a basic community tank and/or spieces tanks with minimum filtration. Example: A 50 gal tank with a filter rated for 50 gallons would not be an ideal set up to put 50 1 inch fish in it.Like mentioned in punmans reply, it all boils down to filtration, spieces, compatability, and maintenance as to what size of tank and what fish you will stock the tank with. Find the fish you like, and then research them for compatability, max size of each fish,and size of tank recomended. Then get a tank 3 to 4 times the size recomended and filtration for 3 to 4 times the size of the tank.

[Gman44]

Back in the day when dinosaurs roamed the earth, the basic rule was 1 inch of fish per gal or 4 inches of fish per square foot of surface area. However this was for a basic community tank and/or spieces tanks with minimum filtration. Example: A 50 gal tank with a filter rated for 50 gallons would not be an ideal set up to put 50 1 inch fish in it.Like mentioned in punmans reply, it all boils down to filtration, spieces, compatability, and maintenance as to what size of tank and what fish you will stock the tank with. Find the fish you like, and then research them for compatability, max size of each fish,and size of tank recomended. Then get a tank 3 to 4 times the size recomended and filtration for 3 to 4 times the size of the tank.

Sounds like go big or stay home!

[JLake]

over filtration never hurt anyone

[randy]

over filtration never hurt anyone

Not so sure about that, lost a few fry to filters!

[yhbae]

inch per gallon absolutely doesn't work for 90% of the cases. Fish bioload is more proportional to the weight of the fish, not the length. Plus, as someone else mentioned above, some fishes are more active than others, and some will create more mess than others. And as mentioned again, some require more space than others. So in some cases, bioload-wise it might be enough but there may not be enough space.

AqAdvisor uses all of these aspects. Out of more than 40 attributes for each species, two of them are called "bioload factor" and "minimum tank size". Every species has its own set of attributes independent from each other.

Edited April 10, 2010 by yhbae

[Danno1986]

It helps to add fish over time. Dont put them all in at once. Get a few let the bioload catch up, then get some more. If your water conditions start to fall you have to many. Fairly simple.

[JLake]

over filtration never hurt anyone

Not so sure about that, lost a few fry to filters!

If you want to save your fry, put a sponge over the intake or use sponge filters, I still swear by double or even triple the recommended filtration. On my 90 gallon I have filters that are rated for almost a 300 gallon tank.And that tank only has 20 fish and half are perticolas or plecos.

[JLake]

Im also a huge fan of mostly biological filtration. My mechanical filtration is "ME" sucking up debris and poops. I just jam cannisters full of bio max or scrubbies. Chemical filtration, I dont use charcoal without a reason too, ie. removing medicine, or some emergency.

[T Dawg]

over filtration never hurt anyone

Not so sure about that, lost a few fry to filters!

That is an issue with filters in general, as apposed to an issue with over filtration. My fry seem to do better in the filter, so I leave them alone and dump them back in the big tank when I clean the filters.

I now use media bags over the filter intakes to keep the fry in the tank. They reduce the flow less, are easier to keep clean, and don't let any through.

If you wallet can take the price and your fish can take the current you don't have too much filtration.