# How determine when overstocked?



## snickle (Apr 8, 2007)

Is there an objective way to determine when you are approaching the max bio-load on a tank?

With a non-planted or lightly planted, I would think if you are at 0 ammonia, 0 nitrites and 25% weekly water change keeps you in the 20-30ppm you are okay.

How about heavily planted?


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## furballi (Feb 2, 2007)

A properly stocked tank should run well without filter. The key variable is surface area of the tank per linear inch of fish. In general, you should allocate at least 10 to 12 square inches of surface area per linear inch of fish (tetras, guppies, barbs, or equivalent). Wide-body fish (angelfish or discus) should have at least 30 square inches per linear inch.

You should also change at least 50% of the water each week. Plants alone cannot remove all the contaminants from the water column.


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## Tsquare (Feb 9, 2007)

I figured out I messed up this AM. How stupid could I be? Don't answer that.
Gene


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## vicpinto (Mar 27, 2007)

Tsquare said:


> Now I am concerned. I have a 30 gal long 12"X36"X 16" high. This would mean I could have 1 3" or
> 3 1" fish. This seems very sparse to me.
> Gene


No. Using Furballi's equation you would have 12x36=432 square inches total surface area of your aquarium. 432 square inches/12 square inches per fish = 36 linear inches of fish or 43.2 linear inches of fish if you use less conservative 10 square inches per fish.


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## furballi (Feb 2, 2007)

You can overstock by adding a powerful filter, but the tank will have a very low SAFETY FACTOR. The water will quickly pollute, which will place addition load on the fish's natural immune system. 

12 x 36 = 432 sq inches...about 24 cards or a pair of grown discus (6 to 7 inches).


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## BryceM (Nov 6, 2005)

When it comes to stocking, there are no hard and fast rules. The inch-per-gallon guide isn't all that useful. You certainly couldn't take a 29" long fish and expect it to do well in a 29g tank. That same tank could probably contain 40 or 50 little danios or tetras quite nicely.

For me, the most important factor is the mass of the fish. Tetras, loaches, and the like are slender. How many neon tetras would it take to weigh as much as a single 6" oscar? Probably several hundred. Four or five angelfish is a decent load for a 55g tank, even if they only total 20" in length.

How much you feed is also a factor. If you're heavy-handed with high protein or live foods, expect to see problems with even a lightly stocked tank.

In general, planted tanks do best with a relatively small fish load. There are fewer algae issues and it just looks more natural. Too many dissimilar fish distract from the overall layout.

If you're even thinking about your current stocking level, chances are you're already "over the limit".


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## snickle (Apr 8, 2007)

With a 90G I have plenty of surface area. I am not currently overstocked, by almost any general rule.

What I am trying to get at is what is an indicator that you might be stretching the max bio-load of the tank. 

I personally do not believe in weekly 50% water changes, though with my setup on my 90G I can do it unattended in an hour. I aim for 25% weekly.

As fish grow the bio-load changes, it would be nice to have a testable measure, that would also help with bio-load from over-feeding.


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## DonaldmBoyer (Aug 18, 2005)

The only objective way to test this, that I know of, is by testing your nitrates, nitrites, and ammonia levels using test strips or test tube indicators. If the bioload is too high, one or all of those three will show spikes, and then you will know that your bioload is too much. I suppose you could do it that way.......I wouldn't recommend it, though. You could experience a ton of fish loss using this method.

And no, you don't have to have 50% water changes to have a healthy tank. I only change 5-10% per week, and have never had any problems. Although, there is nothing wrong with changing 50% per week either.....the fish love it! Also, plants love it too as there are trace minerals that they need to grow in the water as well.


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## BryceM (Nov 6, 2005)

Most of us add NO3 to our planted tanks. Doing this invalidates any meaningful attempt at measuring bioload by following the NO3 levels. In a well-lit, CO2 supplemented, heavily planted tank you'd need to be quite overstocked indeed before you'd see climbing NO3 concentrations. The plants just use it too quickly. The tank would be visually overstocked way before it became biologically overstocked - at least if your idea of asthetics is anything like mine.


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## DonaldmBoyer (Aug 18, 2005)

True, guaiac......test strips and indicators would probably only be good for a tank that was pre-cycled. I'm just wondering what snickle is trying to do. Cram as many fish into his tank as possible? I would think that your mind would tell you that enough is enough once you hit 40-50 fish in that 90 gallon.....but that isn't "objective," it is subjective. If you increase the filtration and plant load, you could have well over a 100 fish in that tank without any problem. But as Guaiac suggested, why would you want to? Are you trying to get a nice big shoal of cardinals or something, Snik? Or just asking to ask? This is a bit of an odd question, and frankly, I think it is about to make my mind explode.....why ask the initial question: "Is there an objective way when you are approaching the maximum bio-load?" To what aim?

This is kind of like Lewis Black in one of his routines: "If it weren't for that horse, I would have never gone to school." I'm going to go stab myself in the eye now. Goodbye!


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## furballi (Feb 2, 2007)

snickle said:


> With a 90G I have plenty of surface area. I am not currently overstocked, by almost any general rule.
> 
> What I am trying to get at is what is an indicator that you might be stretching the max bio-load of the tank.
> 
> ...


Fish excrete anti-growth hormones in a small closed-loop environment. There are other harmful subtances in the water column that are not picked up by the traditional test kits. The easiest way to measure the benefit of frequent large water change is to raise baby fish to adulthood. Those with frequent 50% water change 2 to 3x per week will be more robust/larger than those receiving 25% water change. Clean water also places less stress on the fish's natural immune system.

Go to any fish hatchery and ask them how much of the water is replaced every 24 hour.


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## snickle (Apr 8, 2007)

furballi said:


> Fish excrete anti-growth hormones in a small closed-loop environment. There are other harmful subtances in the water column that are not picked up by the traditional test kits. The easiest way to measure the benefit of frequent large water change is to raise baby fish to adulthood. Those with frequent 50% water change 2 to 3x per week will be more robust/larger than those receiving 25% water change. Clean water also places less stress on the fish's natural immune system.
> 
> Go to any fish hatchery and ask them how much of the water is replaced every 24 hour.


I don't disagree with you, but I am not running a fish hatchery and neither are most of the members. I agree the cleaner the water the better. BUt how much water changes is reasonable for the average aquariast?


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## snickle (Apr 8, 2007)

DonaldmBoyer said:


> The only objective way to test this, that I know of, is by testing your nitrates, nitrites, and ammonia levels using test strips or test tube indicators. If the bioload is too high, one or all of those three will show spikes, and then you will know that your bioload is too much. I suppose you could do it that way.......I wouldn't recommend it, though. You could experience a ton of fish loss using this method.
> 
> And no, you don't have to have 50% water changes to have a healthy tank. I only change 5-10% per week, and have never had any problems. Although, there is nothing wrong with changing 50% per week either.....the fish love it! Also, plants love it too as there are trace minerals that they need to grow in the water as well.


I would consider any spike of the ammonia or nitrites an indicator of major overstock. I am really trying to find an indicator to let me know before I am there.


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## snickle (Apr 8, 2007)

guaiac_boy said:


> Most of us add NO3 to our planted tanks. Doing this invalidates any meaningful attempt at measuring bioload by following the NO3 levels. In a well-lit, CO2 supplemented, heavily planted tank you'd need to be quite overstocked indeed before you'd see climbing NO3 concentrations. The plants just use it too quickly. The tank would be visually overstocked way before it became biologically overstocked - at least if your idea of aesthetics is anything like mine.


I am not sure I totally agree with the NO3 bit, but I am still looking for an indicator. My 90G while a heavily planted it is also well fished. The goal of this tank is fish, with enough plants to make it closer to an ideal environment. Not aesthetics. But they do matter.


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## Edward (May 25, 2004)

*What is the most fish waste plants can filter out? *

Planted aquariums can run indefinitely without water changes. Plants remove almost anything from water, but only if they are healthy and water column is not overdosed. For plants to be healthy they must have balanced food. So, if you are running successfully a planted aquarium your plants will always be looking for more elements to take. 

When fish waste amount reaches the limit of what plants can take, NO3 starts accumulating in the water column. High light, CO2 enriched aquariums support much higher fish load. 

Thank you
Edward


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## furballi (Feb 2, 2007)

I had a 20 gal long tank with healthy plants and a few cardinals many years ago. Never changed the water except for a monthly refill to makeup for evaporation. None of the card will exceed 1.2" in length and live for more than one year.

Purchased a 50 gal after college. Since I have more time and $, I also created a semi-automatic water change rig to irrigate my garden. Moved the plants and fish to this new tank. With 50% water change 3x per week, I was able to extend the life expectancy of these eight cards to about two years. 

My oldest card is approaching 7 years old. This fish was purchased from a LFS in Canoga Park, Ca for $2 at 1/3" in length. She's currently 1.8" long (without the tail fin).


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## Edward (May 25, 2004)

Your fish did not live long because of high Calcium and alkalinity levels from your substrate. Not because of old water. Old water can be cleaner then the tap water used to fill up the aquarium. Healthy plants are the best chemical filters. Of course, it's all about balance. One cryptocoryne plant won't be able to handle all the waste from a discus fish.


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## ianmoede (Jan 17, 2005)

Edward said:


> Your fish did not live long because of high Calcium and alkalinity levels from your substrate. Not because of old water. Old water can be cleaner then the tap water used to fill up the aquarium. Healthy plants are the best chemical filters. Of course, it's all about balance. One cryptocoryne plant won't be able to handle all the waste from a discus fish.


Can you back any of that up? Specifically the alkalinity comment. I live in austin, texas. Home of the Edwards Aquifer which is limestone based. Our pH out of tap is around 9. We have extremely high alkalinity and calcium, and have NEVER has any issues with my fish not living long. If anything they arent dying fast enough for me to keep getting the newest most popular ones


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## furballi (Feb 2, 2007)

Been using the same substrate (2 x 50lb bags of gravel) and water since I first started in this hobby. This gravel does not decompose calcium or other material that would raise the alkaline level in the water column. High calcium and high alkalinity will prevent reproduction but they DO NOT kill cards. I've raised 30 days old cards in 8.2pH with 10 KH water. No problem.

Most our local water come from the Colorado...hard alkaline water with plenty of calcium.


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## Markalot (Feb 14, 2007)

Howdy,

one thing I see left out of this discussion is fish stress. Limits of filtration are one thing, but if you stress the fish by overcrowding they will become more susceptible to usually harmless diseases or beasties that normally live in your tank. A stressed fish will get sick.

A schooling fish might enjoy a crowd while a fish who requires his own territory may get stressed. It's the in your face factor. Typically when this question is raised it's because someone wants to put a cool new fish in the tank. Sure, you'll get people who say it's ok, but you'll probably find that in a few months your having fish health problems. Stress is a hard thing to prove.

Know your fish, know their needs, research compatibility, stock accordingly.


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## furballi (Feb 2, 2007)

I use the 12 sq inches per linear inch of fish (slim body). Wide body fish get 30 sq inches per linear inch.

Most fish will put up with other kinds. What to look for when it comes to incompatibility? Fish A chasing fish B. Fish A is full at meal time while fish B is circling below looking for food.

I've had cards (semi-schooling) with betta (semi-territorial). No problemo. There are no concrete rule to follow. Use common sense and good judgment because fish also have their own personality.


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## BryceM (Nov 6, 2005)

How to determine when overstocked = How close to the cliff can you drive? Why not stay away from the edge and enjoy the scenery?


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## standoyo (Aug 25, 2005)

Lol Guaic! 
IMHO you're overstocked when your fish blocks the scenery.

Nature pictures show a small herd of deer in an opening a large pine forest.
Just like we have a few monkeys here in overgrown jungle.

I was taking pictures for the ADA thing and the two heckel discus[4.5"] was in the way of a good composition in a 72G. Kid you not.


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## T-Bone (Nov 23, 2005)

I know I'm beating a dead horse here. But the inch per gallon rule works better when fish Volume is factored in. An 8 inch oscar takes up much more space then ( 8 ) - 1 inch tetra's

________________________________________________________________________________

Length x Height x Width = Volume

*Neon tetra*
1" x 1/4" x 1/4" = 0.0625'' cubed
0.0625 x ( 8 ) neons = 0.5" cubed

*(1) 8" oscar*

8" x 3" x 1.5'' = 36" cubed

_____________________________________________________________

My figures are estimates (Ive never actually measured a neons, or an oscars, width or height) but the point is clear 8 neons take up waaay less space then (1) 8" oscar. Thats why you can have many more small fish, then big fish. Expecting the public to do equasions like this is asking alot though (even though this is 8th grade[or less] math)


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## furballi (Feb 2, 2007)

I'm an experience discus breeder and know how to keep them happy using the local tap water. Yes, they need a lot of clean water and space. That's why I currently stock cards and neons.


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## Edward (May 25, 2004)

furballi said:


> I've raised 30 days old cards in 8.2pH with 10 KH water. No problem.





furballi said:


> I'm an experience discus breeder and know how to keep them happy using the local tap water. Yes, they need a lot of clean water and space. That's why I currently stock cards and neons.


 This is how we see South American fish Discus, Cardinals and Neons living in your local tap water at 10 dKH. Sure, they live &#8230; they don't complain &#8230; because, well &#8230; they have no choice &#8230;


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## furballi (Feb 2, 2007)

Edward said:


> This is how we see South American fish Discus, Cardinals and Neons living in your local tap water at 10 dKH. Sure, they live &#8230; they don't complain &#8230; because, well &#8230; they have no choice &#8230;


Neons are dropping eggs in this water. Hmmm, must be a bunch of genetically engineered half-breeds from Fl or Asia. Give me 10KH water any day if it can sustain my cards 7+ years.


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