# Stocking Question: Can I add more?



## Clubber (Aug 6, 2009)

I have 20 black skirt tetras and a bushynose pleco in my 47 column.

Tank is tall...30" but it's only 20" long and 18" deep! Not much of a footprint but it's got height.

Am I currently stocked or can I get away with adding more and if so I'd like suggestions.

Thanks


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## Tazman (Jan 15, 2012)

I would say no to adding anything else. The Pleco creates a lot of waste and you are nearly at your maximum stocking capacity.


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## Clubber (Aug 6, 2009)

edit...thanks


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## Clubber (Aug 6, 2009)

Tazman said:


> I would say no to adding anything else. The Pleco creates a lot of waste and you are nearly at your maximum stocking capacity.


Sorry for the back to back posts but yes I have noticed the pleco produces much waste. I siphon it off the sand regularly.

If I say um, I swapped the bushynose out to another tank in exchange for a few ottos...could I get away with more or some white skirts?


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## Tazman (Jan 15, 2012)

I would say if the pleco wasnt there then the addition of about 7-8 more fish would be absolute max for the tank.

7 additional White skirt would fully stock the tank in my opinion.


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## Fishguy2727 (Dec 22, 2011)

NO ONE can give ANY advice on stocking without knowing water quality. If no one even asks we might as well go back to 1986 and say 1" per gallon.

What is your water change schedule?
What is the nitrate concentration BEFORE a water change? 

If it is under 20ppm or within 10ppm of your tap then you are fine chemically. You have a nice big school in there, are they filling up the tank with their activity? I would not ditch the bristlenose, they are great maintenance fish and are doing a lot of work for you for free at this point. If it was my tank I would probably have something to eat extra food (a trio of small-medium loaches or a school of 6+ cories, I prefer sterbai).


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## Clubber (Aug 6, 2009)

Had no idea which year that 1" per gallon rule in effect. Cool to know! 

For this tank, I remove 30% water and replace it with new water treated with AquaSafe by Tetra. Weekly 1x.

The water has consistently remained as <10ppm for months now.

The black skirts will either be scattered about each one active as he/she swims it's own path, OR, many times they shoal together around the driftwood. They are most active whenever I go near the tank because they think/hope I am going to feed them. When in a shoal, it's tight and there's plenty of room left around them. When they're scattered around seperate, there's not as many empty areas. They do rarely venture to the bottom however.

Pleco sticks to the driftwood 70% of the time, is on the substrate 20% and on the glass 10% of the tank. Rough estimate!


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## Fishguy2727 (Dec 22, 2011)

Sounds good. With that water quality you definitely have room for more if you want it.


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## Byron (Mar 7, 2009)

There are some other factors that should be considered here and that have not been mentioned.

First on the water change, there are reasons far more serious than nitrates for changing water, and these cannot be measured. Pheromones and allomones, urine (a tetra excretes over 30% of its body mass in urine every day), etc. Water must be changed regularly to deal with this, as these things seriously affect fish. No mention is made of the pleco size, but this fish alone would suggest more water should be changed, 50% once weekly wold be my aim.

The minimal surface are, both in terms of the water/air surface and the surface of the tank substrate, work against you in a tall tank as opposed to a longer tank. While greater water volume can help, the area is more important both for the fish's needs physically and for water quality.

Live plants impact significantly on both of the above issues (they help), and these are not mentioned.

This species, Gymnocorymbus ternetzi, is quite an active swimmer when young, but tends to slow down with age more than many other species in the characins, so that is in your favour long-term. But the tall tanks are better suited to sedate fish such as pencilfish, rasbora, etc. that are less active. These types of fish could be in significantly greater numbers in this tank than can more active fish. And always with lots of live plants, which can be very effective in such tanks.

I would not add to what you have.

Byron.


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## 1077 (Apr 16, 2008)

I agree with Byron, oxygen exchange at surface is greater in standard shaped tank's over column tank's due to larger surface area. This would or can,,allow for larger number of fishes to live comfortably over the smaller surface area in column tank's.
As for Bristlenose, or any other so called"Maint fish", one must also factor in the waste created by the fish. And in the case of pleco's,, the waste(poop) created, is equal to the waste created by a group of smaller fish, so there is less of a benefit than one might think from water quality standpoint (more waste ).


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## Fishguy2727 (Dec 22, 2011)

The pleco is a bristlenose, not a common. No need to treat it like a 2' fish.

Yes, although we cannot measure all the other stuff that builds up in a tank's water, they all correlate very well with nitrate unless there is something removing nitrate specifically and not the others (like live plants, nitrate absorbing media, etc.). If the nitrate is kept minimal with adequate water changes then the other things that build up will be kept minimal as well. So that is not an issue. 

Yes, freshwater fish excrete a lot of urine, but since this is freshwater it is very dilute. The small portion of urine that isn't water is ammonia and being consumed by the nitrifying bacteria. 

I do agree that larger water changes are always better (if done properly) so although I do not disagree that 50% every week would be better, the fact that the nitrate concentration/water quality is so good says it is not NEEDed in this tank, yet.

Surface area doesn't matter when it comes to aeration unless the tank is completely stagnant. Any filter or air stone will provide adequate aeration in almost every situation, whether it is 2 square feet of surface area or 12. I do always recommend an air pump in any freshwater tank though. If the filter is your only aeration and it fails at some point (which definitely happens) then you can start losing fish in as few as a couples hours. If you have a strong air pump on the tank it could go a week or more without any issues. 

Yes, any fish creates waste. But if the goal is to reduce waste production then you should get rid of all the fish. A pleco is an extremely valuable member of any tank. They are not only a cool addition (unless you hate them for some reason) but they actually help keep the tank cleaner meaning less work and more enjoying for you. They are more than worth having IME.


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## Byron (Mar 7, 2009)

> Yes, although we cannot measure all the other stuff that builds up in a tank's water, they all correlate very well with nitrate unless there is something removing nitrate specifically and not the others (like live plants, nitrate absorbing media, etc.). If the nitrate is kept minimal with adequate water changes then the other things that build up will be kept minimal as well.
> I do agree that larger water changes are always better (if done properly) so although I do not disagree that 50% every week would be better, the fact that the nitrate concentration/water quality is so good says it is not NEEDed in this tank, yet.


This does not stand up to scientific scrutiny. Nitrate has no relationship with pheromones, allomones, urine, plant alleopathic chemicals, and whatever. Nitrate occurs as a phase in the nitrification cycle. Some of it will be used by certain bacteria and converted into nitrogen gas that is then released into the atmosphere; this has no effect on the other substances mentioned. I have less than 5ppm nitrate in all my tanks, and they are rather heavily stocked. This does not mean I can dispense with water changes until the nitrates rise to 20ppm. The pheromones and allomones and urine released by all those fish is building with or without nitrates.

Urine is not fresh water, and that's all that matters. It is just one more polluting substance in the closed system, and it has to be removed. An aquarium without regular water changes is like living in a sealed room without fresh air. Anyone who has worked in an air-sealed office building knows about this. Regardless of the air conditioning system, it just is not the same as opening the window for fresh air. Like that air, the water in the aquarium becomes stale very quickly. Fish are constantly taking in water via osmosis, and they remove the minerals and expel the waste water along with any pollutants removed by their kidneys. You must get rid of this, and the more the better.


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## Fishguy2727 (Dec 22, 2011)

I am not saying nitrate and the other things that build up and lower water quality are directly related at all, I am saying they correlate very well with each other. Unless there is something else removing nitrate specifically (like live plants or nitrate removing media) the nitrate will build up over time along with (but not causing or caused by) all of those other things. If there are enough water changes being done to keep the nitrate under control then there are enough water changes being done to keep the other things that build up and lower water quality under control as well. 

I do not think that most freshwater tanks have a significant amount of denitrifying bacteria (the ones that consume nitrate and produce nitrogen gas). The only effective method of nitrate export to rely on is water changes. 

The internal salinity of freshwater fish is much higher than the water. This means water is always diffusing into the fish. To compensate and maintain the proper internal salinity their kidneys are always producing large volumes of very dilute urine. Most of their urine is the water that diffused in to them. There are two majors component of their urine, water and ammonia. The water is obviously not a problem. The ammonia is only a problem if the tank is not cycled yet. This means that the urine is not just building up to toxic levels that are only removed by water changes. 

I am not suggesting at all to not do water changes until the nitrate hits 20ppm. I am saying that looking at this tank, its water change schedule, and its nitrate concentration enough water changes are being done at this time with this bioload that there is room for more fish, even with the same water change schedule. With time as the fish grow and more are added this may change, which is why it is important for any aquarist to do large weekly water changes and check the nitrate concentration from time to time to insure the water changes are still keeping up with the bioload. 

I want to make it clear that I highly suggest and rely on large weekly water changes. I have found that if done properly the larger water changes are the better the fish do. I do not think that people should slack off and let their nitrate go up at all. Water quality is one of the two major things we can control in fish tanks (the other is nutrition). By ensuring that water quality is as high as possible we provide the best environment possible for our fish. 

The main question in this thread is whether or not this tank has room for more fish. Some people answered without even asking about water quality or water changes. To me this is even worse than not asking how big the tank is. IME based on the nitrate, water change schedule, current stock, and tank size/shape this tank does have room for more fish.


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## Byron (Mar 7, 2009)

> I am not saying nitrate and the other things that build up and lower water quality are directly related at all, I am saying they correlate very well with each other. Unless there is something else removing nitrate specifically (like live plants or nitrate removing media) the nitrate will build up over time along with (but not causing or caused by) all of those other things. If there are enough water changes being done to keep the nitrate under control then there are enough water changes being done to keep the other things that build up and lower water quality under control as well.


The last sentence is totally inaccurate. The fact that nitrate does not build up, as it does not in my tanks and many others', does not mean the other substances are not building. They are, there is no doubt at all about this; and they have to be removed regularly or the fish will be affected. Nitrates has no relation whatsoever, which is why it cannot be used as any form of guide for water changes.



> The internal salinity of freshwater fish is much higher than the water. This means water is always diffusing into the fish. To compensate and maintain the proper internal salinity their kidneys are always producing large volumes of very dilute urine. Most of their urine is the water that diffused in to them. There are two majors component of their urine, water and ammonia. *The water is obviously not a problem.* The ammonia is only a problem if the tank is not cycled yet. This means that the urine is not just building up to toxic levels that are only removed by water changes.


The sentence in bold is incorrect. I am not going to argue that urine is the same or no worse than fresh water. This makes no sense at all.



> I am not suggesting at all to not do water changes until the nitrate hits 20ppm. I am saying that looking at this tank, its water change schedule, and its nitrate concentration enough water changes are being done at this time with this bioload that there is room for more fish, even with the same water change schedule.


I and I suspect others are not agreeing with this. There are other factors affecting the stocking that have to be brought in to the equation, as I initially mentioned. Given the species and the tank dimensions I do not recommend adding more fish, with or without any water changes which are relevant to the overall picture but not relevant to every facet of that picture. 



> I want to make it clear that I highly suggest and rely on large weekly water changes. I have found that if done properly the larger water changes are the better the fish do. I do not think that people should slack off and let their nitrate go up at all. Water quality is one of the two major things we can control in fish tanks (the other is nutrition). By ensuring that water quality is as high as possible we provide the best environment possible for our fish.


On this we do agree. 



> The main question in this thread is whether or not this tank has room for more fish. Some people answered without even asking about water quality or water changes. To me this is even worse than not asking how big the tank is. IME based on the nitrate, water change schedule, current stock, and tank size/shape this tank does have room for more fish.


I responded to this above.


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## Fishguy2727 (Dec 22, 2011)

So how do you test for all the other things that build up? Yet again, I am not saying they are related or that one causes the other. I am saying they correlate. If nitrate is not getting crazy then the others won't either UNLESS you are doing something to remove nitrate specifically. They both build up over time. They both need to be removed via water changes. Do you have any references to support what you are saying or is it just your idea that you shove down people's throats until they give in and stop questioning you? I would like real data. 

I never said urine = freshwater. A basic understanding of osmosis and diffusion shows that water (not urine) is always going in to the fish. this has to come back out. Although their urine is not pure freshwater (which I never said) most of their urine is just water and not a problem. But apparently it is? The ammonia in their urine is a problem, if the tank isn't cycled. So again, their urine magically building up to toxic levels theoretically is not a problem.


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## Byron (Mar 7, 2009)

> So how do you test for all the other things that build up?


You cant, that is the point, for most of them anyway. Some substances might be possible with very expensive scientific equipment such as a biology lab might have, but even this... I've never heard of any test for pheromones.



> Yet again, I am not saying they are related or that one causes the other. I am saying they correlate. If nitrate is not getting crazy then the others won't either UNLESS you are doing something to remove nitrate specifically.


This is incorrect. Fish release pheromones and allomones naturally. The level depends upon the fish and its behaviour. You can`t measure this, so far as i know, it is just a fact of science. Similarly the plant allelopathic chemicals. With the fish, the pheromones affect others in the species, and the allomones affect other species. These for instance can stunt the fish`s growth, or signal aggression that will stress out other fish terribly. Regular substantial water changes get rid of these so they don`t continue to pile up. Nitrate has no co-relation to these at all.



> I never said urine = freshwater. A basic understanding of osmosis and diffusion shows that water (not urine) is always going in to the fish. this has to come back out. Although their urine is not pure freshwater (which I never said) most of their urine is just water and not a problem. But apparently it is? The ammonia in their urine is a problem, if the tank isn't cycled. So again, their urine magically building up to toxic levels theoretically is not a problem.


I think it is a problem, simply because it is stale water containing substances from the fish, and not fresh clean water.



> Do you have any references to support what you are saying or is it just your idea that you shove down people's throats until they give in and stop questioning you? I would like real data.


For the record, I never give an opinion that is not supported by research of reliable sources. I may offer my experience on something, and will state it as such, so no one can construe it as fact. If what i maintain is incorrect, then the source is incorrect, and with this issue under discussion the sources are biologists and aquarists with considerably more experience than I have. I happen to be preparing an article on water changes, so here is the list of references I have so far (this is a work in progress):

Boruchowitz, David E. (2009), “Time for a Change: A Mathematical Investigation of Water Changes,” _Tropical Fish Hobbyist_, November 2009 (Part 1) and December 2009 (Part 2).

Evans, Mark E. (2004), “The Ins and Outs of Osmosis,” _Tropical Fish Hobbyist_, February 2004.

Muha, Laura (2006), “Fish Growth vs. Tank Size” in ‘The Skeptical Fishkeeper’ column, _Tropical Fish Hobbyist_, December 2006.

Strohmeyer, Carl (2011), “Reasons for Water Changes,” American Aquarium Products website: 
http://www.americanaquariumproducts.com/Aquarium_cleaning.html

“Growth Inhibiting Substance(s) of Fishes,” on the Wet Web Media at http://www.wetwebmedia.com/fwsubwebindex/GrwLmtChems.htm

Anon. 1988. Stunt Work. T.F.H. citation of Daniel Heath and Derek Roff, "Test of Genetic Differentiation in Growth of Stunted and Nonstunted Populations of Yellow Perch and Pumpkinseed.” Transactions of the Am. Fish. Soc. [116(1):98-102]

Drickamer, L.C. Pheromones: Behavioral & Biochemical Aspects. Adv. Comp. Environ. Physiol. 3, 1989, pp. 269-348.

Fenner, Bob-O. 1989. Frequent Partial (what else?) Water Changes. FAMA 4/89. Some self-aggrandizing citation now!

Konstantinov, A.S. & M. Yu Pelipenko. Use of zeolite to remove toxic substances from nitrogen metabolism of fishes. J. Ichthyol., vol. 23, no. 6, pp 159-161, 1983.

Langhammer, Jim. 1976. G.I.S. - G.P.S. - Optimum Crowding, A Possible Synthesis. Tropic Tank Talk. Various issues during the year.

Sprenger, Kappy. 1974. Growth Inhibiting Secretions. Colorado Aquarist. Jan. 1974. Reprint of the original from San Francisco Aquarium Soc.

Stacey, N.E. Role of hormones and pheromones in fish reproductive behavior, An evolutionary perspective. Prentice Hall, Inc. Englewood Cliffs, N.J. 1987, pp. 1-350.


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## Fishguy2727 (Dec 22, 2011)

There is a correlation though. 

Nitrate is produced by fish based on bioload. Their tissues on their own produce a certain amount of nitrogenous waste. The bioload is affected by the weight of the fish, the food being fed (quality and quantity), temperature, etc.). These are the same things that affect the amount of the other things that build up and lower water quality. So although they are not directly related (none cause the other, limit the other, or go hand-in-hand in production, etc.) they do correlate. 

Let me know when that article is finished, I would like to take a look at it.

I really don't see the issue here, we are both saying the same thing in the end, that large weekly water changes are required to maintain high water quality. The only difference is that I am saying that nitrate and all the other things that lower water quality correlate (not directly) and you are saying that since we can't test the others we have to assume that no matter how well nitrate is under control we must assume the others are out of control.


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## Byron (Mar 7, 2009)

Fishguy2727 said:


> The only difference is that I am saying that nitrate and all the other things that lower water quality correlate (not directly) and you are saying that since we can't test the others we have to assume that no matter how well nitrate is under control we must assume the others are out of control.


My position is that the water in any aquarium is continually deterioriating due to the presence of fish. Every day it deterioriates further. And the results of any test will not necessarily indicate this.

The fish load doesn't matter as far as "deterioriation" is concerned, it occurs no matter; but obviously the more fish or the larger the fish or the more non-compatible they are, the faster the deterioriation.

And testing for nitrates may not give you any indication of this deterioriation, since it occurs regardless of nitrates.


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## Fishguy2727 (Dec 22, 2011)

Byron said:


> The fish load doesn't matter as far as "deterioriation" is concerned, it occurs no matter; but obviously the more fish or the larger the fish or the more non-compatible they are, the faster the deterioriation.


So the fish load doesn't matter as far as deterioration is concerned but can increase it? 

Yes, water quality drops as a result of other things besides nitrate. But like all those things nitrate goes up with time as well. So unless something is removing just nitrate it will generally correlate with those other things. Since we cannot test for those other things nitrate is our best indicator of overall water quality even if it isn't 100% (again, unless something is removing just nitrate like live plants, nitrate specific media, denitrators, etc.). If we had a reason too suspect nitrate wasn't truly representing water quality (like the aquarist adding prime daily to keep the nitrate down or there are live plants and the aquarist isn't doing water changes) then we could get overly worried about the other things. 

Are you saying that testing nitrate is pointless because no matter how good the nitrate is we have to assume the others are out of control since we can't test them and prove otherwise?

Correlation does not mean directly related. For example drownings increase with ice cream sales, they are not directly related but are correlated (more pools/swimming in summer time when ice cream sales are higher). Although the two are not directly associated and one does not cause or limit the other, they still correlate.

I think the biggest problem here is that I like to stock heavily IF and ONLY IF the water changes maintain high enough water quality to allow for it, demonstrated by the nitrate concentration. 

Obviously we are just obsessing over a slightly different but effectively exactly the same thing, just bickering over the exact wording at this point. 

Do water changes. Do them every week. Larger is better.


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## Byron (Mar 7, 2009)

Fishguy2727 said:


> So the fish load doesn't matter as far as deterioration is concerned but can increase it?
> 
> Yes, water quality drops as a result of other things besides nitrate. But like all those things nitrate goes up with time as well. So unless something is removing just nitrate it will generally correlate with those other things. Since we cannot test for those other things nitrate is our best indicator of overall water quality even if it isn't 100% (again, unless something is removing just nitrate like live plants, nitrate specific media, denitrators, etc.). If we had a reason too suspect nitrate wasn't truly representing water quality (like the aquarist adding prime daily to keep the nitrate down or there are live plants and the aquarist isn't doing water changes) then we could get overly worried about the other things.
> 
> ...


Perhaps we should take a step back. I think I am sensing some misunderstanding of terms.

The water in an aquarium with one or more fish will deteriorate second by second until the point at which the fish will weaken and finally die. And nitrates may remain zero throughout. And of course, other factors can impact this, such as live plants. Deterioration will be greater with more fish, larger fish, or non-compatible fish [meaning when considering environmental needs of each species, water parameters not being the same for all, aggressiveness, spawning, etc]. The effect on the fish will then increase the smaller the volume of water because the more water the more dilution.

The nitrate as a guide issue is still way off. You cannot use nitrates to judge the water quality. I have 5ppm in some tanks, zero in others. I am convinced i would never see them higher no matter what, simply because of the plants. But I must do weekly water changes to keep the water less polluted for the fish. In nature, fish are rarely exposed to all these pollutants simply because the fish to water volume ratio is so vast, plus the fact that the water in which the fish lives is there one second and gone the next, so the fish is always in "fresh" water. And when one considers that even in these conditions, fish of a species are highly affected by the pheromones they themselves release continually, and to allomones released by other fish, one should be able to fathom just how enormous this all is. 

A small characin will not get close to a predatory angelfish in nature, but we confine these fish to a 4-foot tank and then wonder why the characins are always stressed and die prematurely. Even if the angelfish do not physically attack, they are sending out signals of aggression, and the characins are reading them. I have likened this to putting a cat in a closed room with a vicious dog chained in the corner. The cat will be terrified. It doesn't know the dog can't get it; but it knows what the presence of the dog means for the cat's safety, and this stresses it out.

We know--or should know--that these substances are increasing regularly. It is true that live plants can handle most of them, provided the plant load is up to the task and the fish load is minimal. I recall one writer suggesting that 6 neon tetra in a well-planted 55g tank would balance out and never need water changes. Something to think about.

Byron.


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## Fishguy2727 (Dec 22, 2011)

I agree that in planted tanks the nitrate cannot be considered a guide because they specifically are removed by the plants while all the other things that build up are not. I thought I had made this clear in every post. The nitrate is a good guide IF and ONLY IF there is nothing removing nitrate specifically (live plants, adding prime, using nitrate specific media, using a denitrator, etc.). If this is NOT the case THEN nitrate will still build up over time, just like all the other things.


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## 1077 (Apr 16, 2008)

Fishguy2727 said:


> The pleco is a bristlenose, not a common. No need to treat it like a 2' fish.
> 
> Yes, although we cannot measure all the other stuff that builds up in a tank's water, they all correlate very well with nitrate unless there is something removing nitrate specifically and not the others (like live plants, nitrate absorbing media, etc.). If the nitrate is kept minimal with adequate water changes then the other things that build up will be kept minimal as well. So that is not an issue.
> 
> ...


You have the honor of being the only person I have yet to correspond with,(40 year's) who seem's fairly knowledgeable, that would express that larger surface area provided by standard rectangular tank ,does not provide better oxygen exchange at the surface than column tank. 
Having kept, and am keeping ,various pleco's of all sizes,species,(love them) I can only chuckle at your belief that they somehow keep the tank cleaner.
These maint fish as you call them excrete two to three times the waste of smaller group of fish such as tetra's,barbs, depending on activity level's of particular species.If it's more fish you want, then forget about pleco's for the input from fish to the system is greate than a few smaller tetra like fishes .
Many of them(plecos) require their own diet (omnivores,carnivores,herbivores) for long term health, which can add also to waste created in the tank and most prefer moderate to swift current's which some,, (ok alot) of smaller species don't appreciate.
I also am amused, by your opinion that a simple air pump could support a tank for up to a week with no mention of plant's or bio-load.
Sure ,bacteria on substrate exist's, as well as on decor, but biological oxygen demand(BOD) is also high depending on number's of fish and organic input, and bacteria in filter that shoot's crap's begins to die off fairly quickly,(perhap's sooner than a week) and dead organics are then pumped back into the system once the filter return's to service.
Can create very low oxygen situation until filtration resumes.
Larger surface area is agreed by most, to support better oxygen exchange at surface than smaller surface area, and I have yet to hear any opinion's,nor expierienced anything that would lead me to believe otherwise.
Simple DO meter would provide more accurate assessment than my or your opinion.


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