Aquarium fish size

[sidewinder]

Okay, Peter. I have kept and bred tropical fish for over 40 years. I started out with livebearers and have kept cichlids (Discus, South American, African), and saltwater over the years. I have had tanks from 2 gallons all the way up to 200 gallons.

The simple fact is that tank size, unless ridiculously small, has ZERO bearing on how big a fish gets. Water quality and food quality are the two major issues that affect how large fish get compared to their genetic potential.

S-

 

[Orin]

Okay, Peter. I have kept and bred tropical fish for over 40 years. I started out with livebearers and have kept cichlids (Discus, South American, African), and saltwater over the years. I have had tanks from 2 gallons all the way up to 200 gallons.The simple fact is that tank size, unless ridiculously small, has ZERO bearing on how big a fish gets. Water quality and food quality are the two major issues that affect how large fish get compared to their genetic potential.

S-

I won national aquarium article contests when you were keeping livebearers and have a minireef that's been in contiuous operation since 1989. I also have a 25 year old Tropheus colony. I could spend all day listing various fish, plants and inverts I've propogated but that has little to do with simple facts. I've seen hundreds of "fish rooms" and a number of commerical hatheries and public aquariums behind the scenes. What is your definition of ridiculously small? Versus what fish? I've seen fully mature, mating sushine peacocks at 1.5" that were reared in a 10-gallon (I was impressed though maybe a little saddened). I'm sure you are familiar with stunting. Why does a goldfish in a bowl never grow but the same fish in 50 gallon grow huge? It's because the volume of water and waste versus the surface area required for denitrification is too low. Certainly a goldfish in a 10-gallon with a $200 wet/dry filter may grow as large as it would in a 50-gallon with a sponge filter but to discount aquarium size as immaterial is an attempt to prove a point with no reality. I imagine you've entered grow-out contests if you've been in the hobby as long as you claim and you'd be lying if you said you didn't use the largest aquarium available to you. It is possible to grow fish in small containers with constant replacement of the water as is done daily in fisheries but the actual water that flows through the container is infinately greater than the volume of the container. It's simply a way to get around the chemical problems associated with small aquariums, it doesn't mean people should keep all their fish in 1-gallon cages since they'll get as big as they want anyway.

 

[The_Asa]

Does anyone have sources for any of this?

 

[sidewinder]

Orin,

You are making my point for me. Stunting is caused by poor water quality and poor diet, not by tank size.

S-

 

[Rick]

Orin,You are making my point for me. Stunting is caused by poor water quality and poor diet, not by tank size.

S-

I would say tank size plays a factor too. I have had aquariums and have been fishing my whole life.

 

[Peter Clausen]

Here's what I've learned from this discussion...

While tank size may or may not be the direct factor in whether a fish grows to maximum size, it is the variable that most people can easily control. So, for most people tank size is a factor, because greater quantities of water spoil more slowly than smaller quantities.

So, for most people, upgrading to a larger tank is the easy option. It's a lot more convenient and reasonable than monitoring water quality.

 

[sidewinder]

Peter,

The problem with your logic here is that people that have larger tanks put more fish in them. So the someone that is not going to keep the water quality high in a small tank isn't likely to do so in a large tank either.

Again, tank size in not the issue. It is the keeper and his habits and knowledge. That is what affects water quality and food quality.

S-

 

[Peter Clausen]

First, let me say that I've never kept fish, but...

Scott, let me outline the points made during our discussion and you can decide for yourself where the failure in logic was.

Scott selects topic of discussion to be aquarium fish size.

Scott states that aquarium size does not affect growth of fish and water quality does.

Peter states that a larger tank of water spoils less quickly (making reference to "a fish")

Scott states that larger aquariums entice people into buying more fish, thereby lowering water quality back to what it would have been with one fish in a smaller tank.

Bottom line: if the average hobbyist wants to optimize his chances of producing a big fish, he should put it in a large tank. Obviously, the introduction of various variables like additional fish or a big bucket of poo dumped into the tank will be detrimental. Now, introducing additional variables to this discussion will do the following:

1. change the topic

2. complicate the current topic

In a controlled experiment, we won't change the variables of the experiment halfway through. Nor should we do so in this discussion.

As before, there are two ways of doing things. The perfect way and the convenient way. A larger tank is the easiest option for the average hobbyist with average ambition. Not everybody is going to sit around with a strip of litmus paper or whatever they use to monitor water quality and dip it in every five minutes. Personally, I'm too busy enjoying the posts of mantidforum members to devote that kind of time to fish

I don't see a problem with my logic on the level of this discussion, nor in the big picture (everybody getting along, which was half the point of my previous post). Once again, you are arguing for the sake of arguing. The new points your last post brought to the discussion are extraneous and contentious.

There is a recurrent theme in your posts where you do the following:

1. try to make others wrong, even though they're not contradicting you

2. try to defend your point, even though nobody is attacking it.

I don't disagree that most people that upgrade to a larger tank will want to put more fish in them...UNLESS, of course, their whole point in doing so is to grow the fish they already have to a larger size per the upgrade (which just so happens to be the entire point of this discussion).

And I don't disagree that water quality is the issue.

Of course, this is all fun and interesting if taken with a grain of salt and with an eye towards entertainment. Not everybody enjoys your games as much as I do.

 

[PhilinYuma]

First, let me say that I've never kept fish, but...Bottom line: if the average hobbyist wants to optimize his chances of producing a big fish, he should put it in a large tank.

Yes, that's right! Don't even bother with filtration. Just bore a hole in the tank, put in a standpipe, and have a continuous water change. Add good oxygenation, the maximum optimal temperature, enough live food to ensure that the fish can always eat, low lighting levels to simulate "perspicuous gloom", and you are on the right track to producing a good sized fish.

Like Orin, I have participated in aquarium club "grow outs", and I have seen determined competitors place a Cichlid in a fifty gallon tank in January in the hope of producing a "super fish" at the fall show. Some it was rumored, even tried out secret "growth hormones" which occasionally killed the fish. :huh:

These techniques, growth hormone aside, will produce an optimally sized fish under optimal artificial conditions, but the law of diminishing returns usually tends to prevent the production of a truly humongous one.

Cichlids, like mantids, are usually ambush feeders and need a supply of food that comes to them if they are to conserve the energy necessary for growth. Large carnivorous fish appear to emit pheromones that cause small prey fish to avoid them if the concentration in the water is high enough. We used to bag small fish for shipping in water from a tank that held a large fish and they would be much quieter during shipping (try it!). In the wild, such pheromones are greatly diluted and prey fish are more likely to swim within range. In a tank, even a large one, they will tend to hide or cower in a corner, and the large fish will have to expend energy hunting them down. In that case, and perhaps only in that case, the use of a large tank can be counterproductive.

Perhaps the major limiting factor, though, is the fish's bad habit of only eating when it is hungry. It is much easier to "fatten up" a herbivore than a carnivore.

O.K. guys, that's it. Back to the fray!

 

[sidewinder]

Peter,

Think what you want. But the premise was that tank size is what had a direct affect on fish size. That premise is wrong. It doesn't matter how you rationalize it. It is wrong. It is water quality and food that affects fish size. That is the technical, factual, and academic truth.

Now, there are many factors that cause aquarists to provide less than ideal water conditions. Usually it is too many fish per gallon of water. Often it is not enough regular water changes. Overfeeding can be a factor. Not enough filtration is another. Do you see where this is going? There is the cause and factors that contribute to the cause. The factors that contribute to the cause are not the cause.

Here is the logic being used:

Small tank --> poor water quality --> equals stunted fish

Might as well do this:

Africa --> insufficient food --> starving people

Do all people in Africa starve? Or is it people with insufficient food?

The logic should be:

Poor water quality --> equals stunted fish

and:

Insufficient food --> starving people

This is the point Christian was making and that I am making. My game? I don't know what you are talking about. Excuse me for wanting to be accurate and correct. But, feel free to think that small tanks must mean poor water quality which means fish growth must be stunted.

Scott

 

[PhilinYuma]

Scott:

Just a quick note to say that I think that you are absolutely right, and that you have ably demolished both Peter's pathetic argument and my misguided attempt to agree with it. I would only add that in addition to being "the technical, factual, and academic truth," it is quite possibly the "spiritual and transcendental truth" as well, though that may be going a bit too far; I don't want to overextend your argument.

I look forward to your reply, if any, to this, not only in the interest of furthering my own education, but because I have a sizable bet with another member on what you will say.

Don't let us down!

Oh, and welcome back from Hawaii! Believe me, this forum wasn't the same without your insights!

 

[critterguy]

Therefore while tank size in and of itself does not greatly affect fish growth(as those who have observed hatcheries, catfish farms etc. know), water quality does. However, water quality tends to be a major problem in small tanks...thus, for an average aquarist, yes, small tanks do restrict fish growth.It would be interest to see if they are any psychological/physiological factors that affect fish growth in different enclosure sizes if water volume/quality is the same. I am willing to bet their are. Perhaps fish kept in more restrictive enclosures use up less energy and grow faster. Or maybe the psychological stress of being unable to do certain behaviors could cause stunting. This sounds  like something that I'm sure has been investigated already.

 

[Peter Clausen]

From the standpoint of logic, you are correct Scott. No doubt. I never disagreed that water quality was "the cause", did I? It just doesn't sound like something which is easy to maintain as a constant in a small aquarium. I'm sure it's nearly possible, just not as practical as putting the fish in a larger aquarium. This is approximately what my argument amounted to. Nothing more, nothing less.

I made the reference to games when you put additional fish into my larger aquarium.

Let's hold the water quality variable as a constant and I'll let you guess which direction I'd go from here...

1. my big fish lives in quality water in a 10 gallon tank and I have to change the water weekly.

2. my big fish lives in quality water in a 40 gallon tank and I have to change the water monthly.

But, I am still curious about the surface area point made earlier. Gas exchange/oxygenation provided by larger tanks and whether that might contribute towards fish what it once did for prehistoric dragonflies with 2 foot wingspans? Again, I've never personally had pet fish.

Also, might there be bacterial (the good kind of bacteria) advantages to having a larger tank?

 

[Orin]

From the standpoint of logic, you are correct Scott. No doubt.

No, he actually commits a number of logical fallacies to promote his arguement. He begins by pretending to be an authority and continues with changing subjects and false conclusions. Aquarium size is a primary factor in water quality maintenance but since it is not the only cause he pretends it cannot be true.

 

[sidewinder]

Peter,

If you stock your tank appropriately, it is no harder to keep the water quality high in a small tank than it is in a large tank. In fact, it may be easier because water changes are easier. Overstocking a tank is a problem with 10 gallon tanks just like it is with 100 gallon tanks. For an experienced aquarist, managing the ecosystem in a small tank is not any different than managing it in a large tank. Inexperienced aquarists have no idea how to manage the ecosystem.

Assuming the same proportions, larger tanks do not offer better gas exchange nor do they provide better oxygenation. And you can't get more oxygen in the water than the saturation point. Larger tanks do hold more dissolved oxygen (DO) so you can put more fish into them. But, you can use many methods to increase the DO in the tank. These include:

Using live plants

Limiting bacteria in the tank and the filtration system

Using efficient air diffusers

Big is an ambiguous term. How big is this fish you are raising?

Scott

 

[sidewinder]

No, he actually commits a number of logical fallacies to promote his arguement. He begins by pretending to be an authority and continues with changing subjects and false conclusions. Aquarium size is a primary factor in water quality maintenance but since it is not the only cause he pretends it cannot be true.

Orin,

Please explain the "logical fallacies" I committed. Aquarium size in NOT the issue. It is water quality. Any artificial ecosystem you put fish into can handle only so many fish before the ecosystem starts to fail. This is all proportional. If you put one too many fish in a 10 gallon tank, that is going to cause more problems than putting one too many fish in a 100 gallon tank. But, if you put 10% too many fish in the 10 gallon tank it is not going to cause any more problems than putting 10% too many fish in the 100 gallon tank.

Scott

 

[PhilinYuma]

Let's hold the water quality variable as a constant and I'll let you guess which direction I'd go from here...1. my big fish lives in quality water in a 10 gallon tank and I have to change the water weekly.

2. my big fish lives in quality water in a 40 gallon tank and I have to change the water monthly.

But, I am still curious about the surface area point made earlier. Gas exchange/oxygenation provided by larger tanks and whether that might contribute towards fish what it once did for prehistoric dragonflies with 2 foot wingspans? Again, I've never personally had pet fish.

Also, might there be bacterial (the good kind of bacteria) advantages to having a larger tank?

The following might help, Peter:

Firstly, and I'm not sure that you meant to imply this, no one would increase their aquarium size to to cut down on water changes! But here's the very simple math to show how the use of a larger tank will improve the quality of the water by reducing toxin concentration everything else being equal (no sneaking in extra fish, no buckets of poo!).

Assume that you have a fish that produces 10 units of waste per week in a filterless tank ( and before anyone tries to teach me about the importance of filters, I am simply removing an unquantifiable variable) and you do a 50% water change weekly. After the first water change, that will be 5 units and at the end of the week, before the next change, 15u. and 7.5u after it. The waste will continue to increase until it reaches 20u before the change and 10u after.

At this point you have reached steady state and the waste will range between 10-20 u. until conditions are changed.

Obviously this applies to any water change percentage. In a tank producing 9u of waste/week and getting a 1/3 change, steady state would be achieved at 27:18u.

But the effect of toxins, by definition, depends on concentration. A 10 gallon tank with a steady state of 10:20u will have a toxin concentration of 1-2u/gal. A 50 gallon tank with the same steady state will have a concentration of 0.2-0.4u, which is just an elaborate way of saying what we already knew.

Tank size of itself does not affect the surface:gallon ratio. 20gal tanks can be bought in "high" or "low" configurations, and the "low" version provides a larger surface area and a better ratio. Again, this is not a matter for debate; its simple math. If you take the useless "active carbon" filters (and no, I'm not going to argue that point either)

out of one of those outside, overflow filters and run it, you will improve your gaseous exchange. An air stone will also help to a degree, by breaking up the surface tension, though those pretty bubbles rising to the surface are doing very little to oxygenate the water by diffusion.

Tank size might affect the number of aerobic nitrobacter and nitrosomonas in the water, particularly if you use an under gravel filter, but not enough to significantly effect purification. They need a porous substrate to colonize in, and a LARGE sponge filter (we used to make our own for economy) and an air hose to suck the water through it is one of the best and easiest ways to go. I personally dislike under gravel filters as a substrate, but that is another discussion.

O.K. Peter I trust that that helps and that you consider getting a nice little (50gal) aquarium and raising some fish.

I feel better today. I took my meds.

 

[Peter Clausen]

More interesting reading, guys. Thanks! My daughter wants a chocolate chip starfish and the family as a whole wants seahorses. I'm a few years from making it happen because of some other pet goals vs. time (and they all have relatively new reptile pets). I am especially interested in raising some flower shrimp (if that's the term), one day. The look a lot like flower mantises! I've seen them at a local speciality shop a few times. The seahorse-like pipefish, I think they're called, are also of interest. And the sargosso sea variety lives in my dream tank (only in my dreams).

If anybody is interested in reading about the only aquatic tanks I'm working on, please go here: http://beetleforum.net/forums/index.php?showtopic=19

back to the topic at hand...

When I don't use filters on the aquariums for the water bugs and beetles and especially my giant waterbugs, I notice that the water "fouls" a lot more quickly in small cages than in large ones. I have a lot of bugs to take care of, so even small tasks like water changes add up quickly. I moved my giant waterbugs into a communal 50 gallon after a month or so of being housed separately. The water fouled much more slowly. This is due, no doubt, to the ratios Phil referenced (later, I hooked up a fluval that I had laying around in the garage from a previous life). I've not done even a partial water change on this tank since setting it up, there is a small accumulation of roach carcasses if you really look for them. Of course, it is a more monumental task to change out 50 gallons, but my schedule tends to favor doing a big project once a month when I have so many other things like mantises that require daily upkeep. In my original 5 gallon giant waterbug aquariums, the water would foul ever 5 days or so. The bugs can live in much dirtier water than fish, but I don't want to smell or see dirty water in my tanks.

So yeah, I did mean to imply that I increase aquarium size to cut down on water changes. Then again, I don't raise fish or have much experience with waterbugs either, for that matter. I'm certain the fluval canister is overkill and so is the 50 gallon tank, but I can say that I am enjoying the benefits of no water changes whatsoever. Come to think of it, I did have 13 feeder fish in their for a few weeks. They seemed to favor the bottom of the tank...go figure (the waterbugs the top)!

 

[Katnapper]

If anybody is interested in reading about the only aquatic tanks I'm working on, please go here: http://beetleforum.net/forums/index.php?showtopic=19

Interesting reading about your water beetle setup. Had never really heard of water beetles, lol. Hope you don't have all males...