Overstocking, how to tell?

PumaWard

PumaWard

In loving memory of Meeko
Jul 23, 2003
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First off, what is the best way to judge if you have an overstocked tank?

I mean, I have some sense to it and all, but somethings don't add up.

Like, if by all the stocking rules out there, your tank is overstocked, but you have adequate filtration for adult fish, adequate swimming space for adult fish, and it's pleasing to your own personal eye... is it still overstocked?

For example, you have a planted 10g with a...say... whisper 15g filter on it and it has the following fish in it:
4 cory cats (on the bottom zone)
10 neons (mid zone idealy, lol)
and 3 guppies (top zone, idealy).

By all the stocking "rules" this is overstocked, right? But most the fish will have enough space for swimming because they don't get in the way of each other also.

Or, is this kind of stocking best left to aquarists that have some experience under their belt? (better knowledge of fish and water chemistry)


So, I guess what I am asking is,
How do you guys judge if your own personal tank has the right fish stocking in it?
 
Personally, I feel that the current stocking rules out there today are crap. :o

...I do tend to follow the 1 gallon per fish rule with tanks under 15 gallons just because they tend to have more problems and can be overloaded quickly. So what I mean by that is for small, thin fish like neons, danios, some tetras, and livebearers I go by 1" of fish per gallon...and I dont consider the tail.

I think much of what overstocking represents is when you have high nitrate levels...or when a fish can't grow to it's potential length because of a small tank. In the example of the 10 gallon you gave to us, that sounds ok providing water changes are made often.

...but if, however you told us that you had a goldfish in a 10 gallon I would say thats overstocked simply because a full grown goldfish wouldn't be able to turn around in the tank! Without getting off track, might I add I find the 10 gallons per goldfish rule to be crap also? Newbies (especially on fish forums) are always being told 10 gallons per goldfish and it makes me sick to my stomach because I know that in a few months, the fish will have either died or be stunted...

All and all, I think its up to you as an experienced aquarist to know when your tank has reached it's limits. As for the rest of the community who isn't sure ........ well, thats why we have forums such as this one to ask questions regarding overstocking a tank. :)
 
There's a lot more to stocking than whether or not fish "fit" without bumping into each other.

The goldfish in a 10 would probably be dead long before it got too big to turn. Pollution levels and territorial needs are just as important as physical space.

Nitrates are often used as a telltale for other harder to monitor pollutants. They aren't the only chemical thats going on in there.

17 fish in a 10 seems crowded.
 
Stability

I think the rules for 1"/gallon are a good place to begin. Then, with some knowledge and experience, one can bend the rules.

How do you know? Nitrate levels and general clean up needs are one clue. How do the weekly tests come out? Is nitrate building up? It can happen even in a planted tank if you are overstocked.

Yes, many of us do overstock, most knowingly. Hopefully those that do are aware of the resulting problems with tank stability. You know, somtimes, stuff just happens. A power failure, the filter breaks, some fish gets ill -- then the overstocked tank won't bear up as easily as the understocked tank.

I had an overstocked planted 20H for awhile, it made me really nervous. I ended up running two filters on it, a whisper and a canister, since sometimes after a short power outage the whisper wouldn't start.

I have since moved all those fish into a much larger tank, now very understocked.

I also have some new fish only tanks one of which is overstocked perhaps. I just got auto on backup air pumps for these, but an hours power outage, when corrected will release a deadly cloud of dead bacteria from the dual canister filters. It could be really ugly if I am not home to notice an outage.

The most important thing is that your tank SHOULD NOT be as crowded as the fish store tanks. What you don't see is the large filtrations system and the employees picking out dead fish every morning from their tanks.
 
One other thing we didnt mention here is that the kind of fish plays a huge role...we barely touched up on this but for example, Puma listed:

Neons
Ok, the neons are like less than an inch if you dont count the tails. Not to mention they are super thin.

Guppies
Fairly hardy fish, also theres only three here in the example...

Corydoras
Corydoras are little, and produce minimal waste. If water chemistry is right, they're fairly hardy fish.

Filter
The filter listed was rated for 15 gallon and is in a 10 gallon. This seems good enough.

....So do you see why some might think thats perfectly fine? Sure, it might not make the "1" per gallon rule" but does that mean the tank is overstocked to the American standards? or even canadian for that matter :D
 
I try to look at it this way... what is the space needed for each species in the tank to carry out its courtship... if there is not enough room for all the inhabitants of the tank to have spawning space with out overlapping to much I would consider the tank over crowded.

people compair small bowls to a closet, well I would go further and compair even larger tanks to a dwelling if you had your nieghbors in the same room/space as you would you want to make babies?

now I probably went to far there but I hope I made a point, there is more than sustaining chemical parameters of life to the question of overstocking
 
yeah but some fish dont spawn no matter how large the tank, so that doesnt makes sense...there are to many factors when i t comes to overcrowding, there are no general rules, it depends on each individual situation.
 
Guppies!

Unless the guppies are all of the same gender, the tank will be overstocked soon enough!!

the same gender, AND not already expecting.
 
I think a lot of it has to do with the type of filtration you have also. If you have a filter rated for a 15 in a ten, then i would increase the inch/gallon to 1.5 inch/gallon (15 divided by 10 = 1.5)

I only follow this rule up to a point though, of course, because if you got a ridiculously huge filter for a ten gallon it doesnt really matter
 
And also, getting more filtration isn't enough - it also needs to be acompanied by more water changes (larger and/or more frequent). More filtration means the bacteria will produce the end product - nitrate more and faster!
 
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