Tank size, stock levels?

[bachamp]

I know the simple calculation for working out max stock levels, 1 inch per 1 gallon.

But what is the limiting factor.

If you put a bigger filter in, pump more air through it can you add more fish?

My tank is almost at max stock levels, I plan to get 2 Angles to finish it off. But I only have small fish, and the tank does not look over crowded. The fish seem like they have plenty of room.

My filter does 150 gallons per hour and it is a 25 gallon tank.
I also have a under water filter.

There is plenty of air, both from the under gravel filter and a long air stone running along to length of the tank, also have plants so they should also produce more oxygen.

I know I will not be able to put to many extra fish.

What I want to know is, can you increase stock levels with more air and better filtration or does is tank volume the limiting factor and you want to give you fish plenty of room to move.

I want to have a tank that looks full, but not over populated and at the moment I’m not getting that feel. I have spent time diving around reefs and I have seem many more fish in a smaller area that what is in my tank.


Thanks
:ezpi_wink1:

[Drumachine09]

The 1 inch per Gallon is a maximum, or so ive been told.

[bachamp]

But where did this number come from, from what I can find the limiting factor is the amount of dissolved oxygen. So theoretically if you pump more air in to the water, you should be able to add more oxygen.

There is a limit for how much oxygen can be dissolved in water, CO2 dissolves more easily than oxygen, but with lots of bubbles you should be able to remove the CO2, and replace it with more oxygen.

Also, I wonder what affect do plants have on the oxygen levels. They would do something, but how much I have no idea.

[Drumachine09]

The number is a guidline if you have small fish. The example i was given by a very wise person was this. I have a twenty-nine Gallon tank. I could put 29 1" fish, or 1 29' fish. Which makes more sense? you wouldnt want to approach the 1 inch per gallon limit if you use large fish or fish that will eventually grow large (such as the angels). If you want to max out on the 1 inch per gallon limit, you should only use small fish <2.5". Make more sense?

[Drumachine09]

I have seem many more fish in a smaller area that what is in my tank.:ezpi_wink1:

The thing about that is they have a whole ocean to roam, they chose to stick together. But they wont like to stay that close together for their entire lives. Thats like me sticking you inside of a room this 10 other people. Sure you could all fit, but would you be comfortable?

[Drumachine09]

One more thing. Plants should increase the amount of oxygen in the tank, but if you plan on displacing extra co2 in your tank for oxygen, your plants will not survive.

I am not an expert at plants by ANY means, so it would be smart to check with Jeffs99dime or glasstapper. They both seem to know thier plants.

[bachamp]

I understand what you are saying. I have done all my calculations using the adult size (e.g. angels will grow to 6 inch that is the number I am going to use to calculate stock levels).

My main thing is how did they come up with that rule.

For example, if you only add oxygen to the water by a over flowing filter, than you would not be able to add as much fish. Also if you had a filter that did 5 gallon's per hour for a 55 gallon tank you would also run into trouble if you added to many fish.

If you went the other way though, lots of air, and a really good filter you should be able to add more fish.

[Drumachine09]

Im not doubting that you can keep them alive in such conditions, its will they be stressed out, and will they be happy in such a place. If worse comes to worse, and they fight, it could end up like that REALLY corny movie "Cabin Fever".

[Cichlid_Man]

To be honest with you the 1 inch per gallon is a myth, not a rule.
Drumachine said it correctly when he said small fish you could probably do, but one large one wouldn't cut it.
20 or 25 neons for example, with the filtration you have and sufficient water changes would be fine, but not even one Oscar should go in a 25 gallon.
You have to use your better judgement, do your weekly water changes, aerate well and don't over feed and you'll be fine.

[Drumachine09]

Exactly. I left out the no over feeding and water changes part. Thanks for picking up the slack Cichlid Man.

[bachamp]

That is what I am wondering as well, the number 1 inch per gallon is all over the internet and in books so you would expect it to be right.

To many fish is not a good thing, as you said they will get aggressive, but that will only happen when it get crowded.

Fish like Zebra's will need more room to move as they like to swim around a lot. But fish like Otto cats seem to stay in one spot for a long time so will not need as much.

Lets just say (to make it easy) that both Zebras and Neon’s are the same size, 1 inch. If you have a 29 gallon tank, you could put 29 neon’s in their but since the zebras move around a lot more you would not want to put 29 in their because they need more room. It would not look right. Any you would probably run into problems.

1 inch per gallon is not taking into any thing else into account, only tank size, not fish type or personally, filtration, aeration, amount of gravel, and other adamants, amount of water changes and other tank maintenance. So really it could not be very accurate.

Sorry I spend to much time typing that I dont get to read to other replies

[Drumachine09]

I personaly wouldnt exceed the inch per gallon limit even if all of my fish were lazy. You also have to take into account the amount of waste 30 fish could accumulate.

[bachamp]

You would need a good filter as well.

Im not really thinking of exceeding the limit, just wondering where it came from and what limits the stock. And if it is possible to raise that limit.

[Drumachine09]

Even good filters cant remove large paricles of refuse such as fish waste. I wouldnt approach the limit if i were you.

[bachamp]

Not really asking if I should exceed the limit more trying to find out where that number came from and to get a better understanding about the aquarium limitations.

[Drumachine09]

Ohhhh. I dont know.

[Glasstapper]

Most of what I was going to advise has already been said. Well done, guys!

If you are looking to fully stock a tank, you definitely need a filter that is made for a tank twice the size. Example: you would need a filter from a 60 gallon tank to keep a 30 gallon clean. Or you could get two 30 gallon filters and turn their flow at halfway so you don't have a hurricane in your tank.

Those filters alone would provide enough aeration for your fish to breathe and your plants to survive. Plants need CO2 to live, but if you're pumping tons of oxygen in there, your plants will starve and die. I like bubbles, too, but I need to know to say when so my Java Fern doesn't crap out on me.

The general rule of 1 inch of fish per gallon is just that...general. I find it really only applies to small and/or flat fish. Now even though an angelfish is flat, one angelfish would require at least 5 gallons of water and a tall tank to allow for growth.

If you're tank is overstocked, your fish will be upset that there isn't enough room to hide and find some peace when they want. When fish get upset, they get stressed. When they get stressed, they get sick. Sickness spreads and boom. disaster. also, with a fully stocked tank, be prepared to do many large water changes with gravel siphoning.

I know I've repeated some things already mentioned, but I hope everyone's comments have helped you.

[Glasstapper]

Also, I've heard that some cichlid tanks can get away with slightly overstocking, but I don't know very much about those. Maybe one of our veterans here can better explain the limits, species, and maintenance. If you want to have a "full" looking tank, maybe you could try that.

[bachamp]

something to remember with pumping air in is that it contains co2 (getting more by the day) as well as oxygen so I dont think to many bubbles is a bad thing expaccally for plants.

[bachamp]

I have a lot of places to hide in my tank, a lawn on the bottom, wood with big holes in it, rock caves. Otto cats can go missing for days.

[kimmers318]

In my opinion a good rule of thumb for whether your tank can handle more would be first to observe, as you obviously have done. Do the fish look like they have plenty of room.....no territory issues or squabbles because they constantly run into each other. Second, watch your water parameters closely for a month.....do you ever see ammonia or nitrites? If so, your tank isn't handling the load you have well. How high do your nitrates get before your regular tank change is done? Nitrates are the end result of the whole cycle, and as they build they become worse and worse. If you are regularly seeing nitrate readings of 20ppm or higher just before a water change, your tank probably has all the load it can handle. Having said that, if you don't see higher nitrate readings, you may be able to add more fish, just watch for compatibility issues, each fish has it's own personality. And of course, the different types of fish, and the levels they occupy play a huge part in it. My bristlenose could care less how many fish are in a tank with him....he sticks to himself sucking around the tank. My dwarf puffers on the other hand will not tolerate too many others in there territory even though they are about a 1/4 of the size! In my 10 gal I have 3 dwarf puffers....max size just over an inch.....if you go by the inch per gal rule I should be able to have at least 3-4 more.....but they would maim or kill each other.
Hope that helps. As for where the inch per gal rule came from...have no clue, but have to wonder if it just wasn't someone's idea to give petstores a "guideline" to tell their customers. And we know most of them don't care about the end result of the fish they sell.

[Cichlid_Man]

Great posts Kimmers/Glasstapper/Drumachine.
Just to add one thing. Something was mentioned regarding Cichlids and being able to over stock.
That is true, at least with the African Cichlids, not sure about others.
The reason is overstocking can reduce aggression and actually enhance breeding, providing there are lots of hiding spaces.
It still isn't suggested to overstock. Breeders do it but usually change out 90% of the water daily!
Everything here has been covered very well so I will say this last thing.
Go slowly when adding fish regardless of what species you get.
You want your tank to be able to handle the amount of fish you put in so you don't get ammonia or nitrate spikes.
As you slowly add fish, you will see how they react, and you can determine if you want more or not.
I personally would not even come close to the one inch "rule", even if it were neons.
I have a 30 gallon and I have 4 swordstails at about 1 1/2 inches each, and I have 6 Lemon Tetra at about 2 inches each, and a 5 inch Pleco.
That comes to about 23 inches of fish. There is plenty of activity in the tank and I wouldn't add more.

[kes]

I'm worried that my tank has become 'over quota'.. I have a 30 gallon (us) rectangle tank with two filters running and plenty of aeration and currently I have:

1 small butterly loach
2 zebra/2 leopard danios
7 neon tetras
2 bolivian rams
2 sajica cichlids
3 rosy barbs
3 corydoras
4 platys
3 opaline gouramis

I think I was missold the barbs and the opalines under the advice that full grown they would be about 2" max (Ha!) and I aquired the platys.

My water levels are all perfect, I have no algae problem and the fish all seem quite happy, I just feel this may come and bite me on the bum sooner or later.. I did try and give the platys and opalines to a couple of LFS but they didn't have room to quarantine them.

I've been up and running nearly six months now and *touch wood* all my fish have stayed very healthy and there's no aggression problems..I have added them all very cautiously.

What do you guys think I should do?

[jeffs99dime]

I'm worried that my tank has become 'over quota'.. I have a 30 gallon (us) rectangle tank with two filters running and plenty of aeration and currently I have:

1 small butterly loach
2 zebra/2 leopard danios
7 neon tetras
2 bolivian rams
2 sajica cichlids
3 rosy barbs
3 corydoras
4 platys
3 opaline gouramis

I think I was missold the barbs and the opalines under the advice that full grown they would be about 2" max (Ha!) and I aquired the platys.

My water levels are all perfect, I have no algae problem and the fish all seem quite happy, I just feel this may come and bite me on the bum sooner or later.. I did try and give the platys and opalines to a couple of LFS but they didn't have room to quarantine them.

I've been up and running nearly six months now and *touch wood* all my fish have stayed very healthy and there's no aggression problems..I have added them all very cautiously.

What do you guys think I should do?

just keep doing what your doing. keep an eye on all fish, water parameters, filters, etc. i would not add any more fish though.

[kes]

Thanks, they look ok at the moment. I have ensured that all the territorial ones have caves and rocks to hide in and make their 'home' and the danios, tetras and barbs seem to do their own thing and, all in all, it seems pretty harmonious!

[Lady Hobbs]

I don't believe you can read the requirements for stocking levels and follow it to the letter. The 1" of fish per gallon only applies to small fish at their max growth. I think it's a ridiculous rule and I don't know who dreamed that rule up frankly.

All fish have different requirements. Some fish are slow swimmers and don't take up a lot of room but you have skoalers who are fast swimmers and need more room. Crowded fish are not happy fish and often will become stressed, ill or ornery when in crowded conditions. They need the room to act as they would in the wild.

Mating will bring on another whole problem with more aggressive and keeping all others on one side of the tank.

I would not even apply this rule to Tetra's who are skoalers and want some space to do their thing. I certainly would not put 20 Tetra's in a 20 gallon tank. You have to look at your fish, see that they have plenty of room before adding any more. Stocking slowly will give you ample time to see they are all happy.

[jeffs99dime]

I don't believe you can read the requirements for stocking levels and follow it to the letter. The 1" of fish per gallon only applies to small fish at their max growth. I think it's a ridiculous rule and I don't know who dreamed that rule up frankly.

All fish have different requirements. Some fish are slow swimmers and don't take up a lot of room but you have skoalers who are fast swimmers and need more room. Crowded fish are not happy fish and often will become stressed, ill or ornery when in crowded conditions. They need the room to act as they would in the wild.

Mating will bring on another whole problem with more aggressive and keeping all others on one side of the tank.

I would not even apply this rule to Tetra's who are skoalers and want some space to do their thing. I certainly would not put 20 Tetra's in a 20 gallon tank. You have to look at your fish, see that they have plenty of room before adding any more. Stocking slowly will give you ample time to see they are all happy.

that rule is stupid!!!! whoever came up with it should be beaten! lol

[Sasquatch]

I don't think that it's that stupid of a rule, but it should be taken for what it is, a "rule of thumb".

What is represents is an approximation of the amount of biomass you can have in an aquarium. More than 1" of fish per gallon and you're running the risk of you're biological filtration not being able to handle the load and any little perturbation (like a filter stopping due to power outage) could lead to very serious repercusions. If you're below the 1" per gallon, you have more room to maneuver if something goes wrong.

But like all "rules of thumb" it's only a general guideline. It doesn't take into account the behaviour of the fish or the fact that a 12" fish will produce more waste products than 12 1" fish. That's up to the individual who has to know the requirements for his fish, what his filtration capacity is and the behavioural caracteristics of the fish he keeps.

[jeffs99dime]

I don't think that it's that stupid of a rule, but it should be taken for what it is, a "rule of thumb".

What is represents is an approximation of the amount of biomass you can have in an aquarium. More than 1" of fish per gallon and you're running the risk of you're biological filtration not being able to handle the load and any little perturbation (like a filter stopping due to power outage) could lead to very serious repercusions. If you're below the 1" per gallon, you have more room to maneuver if something goes wrong.

But like all "rules of thumb" it's only a general guideline. It doesn't take into account the behaviour of the fish or the fact that a 12" fish will produce more waste products than 12 1" fish. That's up to the individual who has to know the requirements for his fish, what his filtration capacity is and the behavioural caracteristics of the fish he keeps.

i say it is stupid because people follow it that don't know any better. newbies don't realize that it's a guideline and so they think it's the right way to go about things.

[Sasquatch]

i say it is stupid because people follow it that don't know any better. newbies don't realize that it's a guideline and so they think it's the right way to go about things.

This may seem a bit harsh, but it's not the rule that's stupid, it's the people who don't know any better. They follow it blindly and don't try to improve their knowledge, then get all miffed when someone points out their mistakes.

I've had an aquarium for a little over two months. Since then, I've bought two books, signed up to three forums, looked at a whole bunch of other websites. This despite two years of maintaining and breeding fathead minnows (people are always surprised when I tell them I have over 5000 kids!thumbs2: ) and over eight years of training as a biologist.

I built a 150 gallon recuirculating system with 9 different aquariums from the ground up. Produced over 200 new fatheads a day, fed them and raised them up to adults (or sacrificed them for my master work) and only once had an important loss of fish.

When I put two platies in a 10g tank, it was a whole other thing and I realized that my previous experiences were only worth so much. So I went and learned (and am still learning) what I needed and now things are going well.

The 1" rule is a decent guideline, but you have to go beyond that. It's when you don't that you have problems.

[bachamp]

It is good to see that some people are thinking about it.

So without knowing what fish I have in my tank, what things should I be looking at before I buy my next fish?

My tank has never seen any ammonia, even during cycling. But it has cycled, there has been a decussion about it in this forum, [Only Registered Users Can See Links.]

My tank in not crowded, there are no signes of aggression, and there are plenty of places to hide.

I have Zebras, Neons, Ottos, and Gourami.
If I get some extra fish it will be some very young Angle's.

All the fish are young and I expect them to grow, but I also expect to get another tank soon, so I will move some into their when they get older.

[Abbeys_Mom]

Just something to add. The one inch of fish per gallon rule has been around forever. It was made for tanks back when filtration and aeration were not what they are today. But it is still a valid guideline. It is not the be all and end all. There are exceptions to every rule. Large fish need more room, some small fish need less room. But as far as community fish, it gives you a reference point to work with.

Just my Opinion.