Stunting Fish Growth

We have all heard that keeping fish in a tank that is too small causes "stunting". I've seen more than one study that says tank size is only a factor when it restricts the fish physically. I've also seen fish that were grown to full size in tanks that were "too small" for them. I've never seen a stunted fish. That is because because water conditions from an inadequately cared for aquarium kill them. These studies all point to water conditions as being a major cause. After all, that is why we filter our water and do water changes, to keep the quality good. As fish get large, it becomes harder and harder to keep the parameters where they should be. I've actually observed fish grow to the point when the tanks physical size might start having an effect on their physiology but those were extremes where the fish had trouble turning around without having to do a K-turn. There is more than one way to keep water conditions ideal in a tank that is too small and fish will outgrow it before stunting starts.

So, tank size alone won't cause stunting until the fish have their movement physically limited. It should be obvious that the fish has outgrown the tank well before that happens. What causes the stunting before that point is reached is poor water conditions or malnourishment.

 

That's true, as far as it goes, but tank size is definitely a contributing factor. Is it wise to tell someone that it's perfectly ok to keep a common pleco in a 20 gallon tank because tank size isn't the direct cause of stunting? I don't think so. Even if the person is willing to do multiple water changes a day to maintain water quality I would call that cruel, even if it didn't cause stunting.

I would also have to wonder what precisely it is in the water that is causing the stunting. Are water changes enough? How many are enough? Are any of us equipped to measure that quantity even if we knew what it was? Personally, in giving advice, I would err on the side of caution and just tell people to get the bigger tank. Especially for newbies who are maybe more likely to jump at the option to keep their smaller tank thinking that they can rest easy knowing that, technically speaking, the tank size is not going to stunt their fish.

 

Tank size can be the reason for bad water quality, which can then lead to stunting.
This is a pretty overdone topic.

 

That's true, as far as it goes, but tank size is definitely a contributing factor. Is it wise to tell someone that it's perfectly ok to keep a common pleco in a 20 gallon tank because tank size isn't the direct cause of stunting? I don't think so. Even if the person is willing to do multiple water changes a day to maintain water quality I would call that cruel, even if it didn't cause stunting.

But so many people do say it causes stunting. How does that explain why fish stores and public aquariums can keep large fish in smaller than recommended tank sizes? There are ways other than daily or even hourly water changes to keep the water conditions ideal. That tank with the large fish could have a filter capacity that is just as large as the tank. Something the average hobbyist doesn't account for.

Do you think it is cruel to overstock a tank that mimics as much as possible the natural surroundings, diet, and water conditions? These fish don't get stunted, they grow, they thrive, they breed, and otherwise behave pretty much as they would in the wild. I think these fish are better off than they would be living in what most would provide in the home aquarium.

 

In extreme cases though, the tank size does directly cause the stunting. It doesn't matter if you change a common goldfish's water every single day and keep it PERFECT. They will never reach a foot long in a bowl that isn't a foot long....right?

 

I think you're splitting hairs. I'm aware of the huge filtration systems behind the curtain at public aquaria and so are you, but is the average or beginner hobbyist? No.

I think that setting a minimum tank size is a safety measure for the fish because if filtration is not up to snuff then the fish will be stunted. Whether it was caused directly or indirectly by tank size really doesn't matter.

 

In extreme cases though, the tank size does directly cause the stunting. It doesn't matter if you change a common goldfish's water every single day and keep it PERFECT. They will never reach a foot long in a bowl that isn't a foot long....right?

I agree and that was covered in the first post.

I think you're splitting hairs. I'm aware of the huge filtration systems behind the curtain at public aquaria and so are you, but is the average or beginner hobbyist? No.

I think that setting a minimum tank size is a safety measure for the fish because if filtration is not up to snuff then the fish will be stunted. Whether it was caused directly or indirectly by tank size really doesn't matter.

How often have you actually seen stunting? I know I've only seen it a couple of times.

Why? Because the fish usually die from the bad water conditions before stunting from the water conditions can take affect.

One more question:
Why is it stunting is only mentioned with larger species when overstocking small species has the same potential for stunting? When speaking of the smaller species, water quality is usually mentioned, but it is even more of a concern for the larger species.

 

I am one who will just put out one sentence saying that too small of a tank can cause stunting. Mostly because I don't always have the time to write a several paragraph explanation, Most do in fact understand when others say the words "stunting."

With smaller fish that are inappropriate for example neon tetras in a ten gallon. I usually mention the overstocking, and the bad water conditions that will most likely happen. That's actually what I usually see mentioned by others too.

As far as filtration goes, you can have tons of filtration, but that won't give a fish more room to swim. It's the room to swim that is the important part when it comes to tank size.

 

I've seen it a few times, that I know of. Probably seen it far more often than I realized though. I mean, how often have you observed your aquarium fishes in the wild and compared them to the captive fish? Do they grow at the same rates and to the same sizes? Externally they may seem "normal" but normal compared to what? Are they normal inside? Mentally? How many aspects of a fish are stunted by being kept in too small a tank?

As to your second question, only a guess but a fish that's going to be a giant is less likely to be able to find a suitably-sized home and is more likely to end up stunted. The number of people who have 5 gallon tanks far exceeds the number of people who have 300 gallon tanks. Stunting is less likely to be an issue with a small fish than a large one. Plus a quick comparison of lifespans seems to show that lifespan is proportional to size. Large fish tend to live longer. They have more of a chance to suffer from stunting.

 

How many aspects of a fish are stunted by being kept in too small a tank?

Until it becomes physically restrictive, none. It's the water conditions.

As to your second question, only a guess but a fish that's going to be a giant is less likely to be able to find a suitably-sized home and is more likely to end up stunted. The number of people who have 5 gallon tanks far exceeds the number of people who have 300 gallon tanks. Stunting is less likely to be an issue with a small fish than a large one. Plus a quick comparison of lifespans seems to show that lifespan is proportional to size. Large fish tend to live longer. They have more of a chance to suffer from stunting.

Aren't smaller fish just as likely to be stunted from overcrowding and inadequate filtration or maybe even more so? Probably not, because the water conditions would more than likely kill them before that becomes a factor.

How do you tell how many is too many? When water conditions go south.

 

I still say you're splitting hairs. The water conditions are related to the size of the tank. Too small a tank and your water conditions "go south" as you put it in a greater hurry. If you actually understood what I was saying you'd know I was asking what about a fish is affected? It's not just the physical size of the fish that can be stunted.

To your second question, reread what I wrote. The answer is in there.

 

It's a well known and well researched scientific fact that fish produce pheromones which stunt growth. The more they're allowed to build up in the water, the more stunting occurs. It also depends on which species are kept together. Cichlids for example have evolved pheromones that will also stunt closely related spp but will not stunt prey species (non cichlids).

 

I still say you're splitting hairs. The water conditions are related to the size of the tank. Too small a tank and your water conditions "go south" as you put it in a greater hurry.

So, you are agreeing with me. It's the water conditions that affect the fish. There are too many other factors to say that the size of the tank has a direct effect. Why does it feel like you are arguing with me?

It's a well known and well researched scientific fact that fish produce pheromones which stunt growth. The more they're allowed to build up in the water, the more stunting occurs. It also depends on which species are kept together. Cichlids for example have evolved pheromones that will also stunt closely related spp but will not stunt prey species (non cichlids).

Okay, I thought that was a myth but my memory wires got crossed a bit. It is true but hardly a concern.

Again, the size of the tank is only a catalyst at best. It only serves to facilitate/concentrate any buildup. It should be noted that even minimal regular water changes prevent the buildup of them. Here is an interesting/humorous explanation FYI:
http://wetwebmedia.com/FWSubWebIndex/GrwLmtChems.htm

In these days of large weekly water changes, they have no chance to build up.

 

In these days of large weekly water changes, they have no chance to build up.

If the waterchanges are weekly these chemicals have all week to build up. That's why tank size causes stunting long before the fish is physically restricted by it. Grow a large Oreochromis for example in a 180 and it will reach 18". Grow 20 Oreochromis in a 180 and they'll stop growing at 6". How do you explain that if the buildup of growth inhibiting substances is negligible?

Oreochromis are an extreme example. They limit their own maximum size with growth inhibitors according to the personal space they will need, and not because the tank size is too small for them individually. An extreme example, but most if not all cichlids at least, produce these substances, so they are having some effect.

Ask any professional breeder/grower. The main factor affecting fish growth aside from food is water changes, ie dilution of growth inhibitors.

 

How do you explain that if the buildup of growth inhibiting substances is negligible?

Simple, not enough water changes.

Why are you bringing up an extreme example when so far we have been talking in generalities? It's a moot point. Those substances can easily be brought out of the equation and again the tank is only a catalyst to concentrate those substances. A 180 gallon tank could have an actual capacity of well over that, if on a system. Also, I have no problem with the fact that there are always examples of the exception to any generality. I've seen the "rules of thumb" broken many times by the "laws of nature".

Again, I think you also are agreeing with me that size alone doesn't matter.

 

I personally believe that size alone can matter greatly in a fish's health and happiness. My betta is currently in a five gallon, water conditions are great, lots of plants, fed a varied diet. She still swims the entire five gallons, uses every small inch of it to the point that I am going to be putting her into a ten gallon. I think she will be happier in the bigger ten gallon. To me happiness of the fish is part of the health.

 

Simple, not enough water changes.

Why are you bringing up an extreme example when so far we have been talking in generalities? It's a moot point. Those substances can easily be brought out of the equation and again the tank is only a catalyst to concentrate those substances. A 180 gallon tank could have an actual capacity of well over that, if on a system. Also, I have no problem with the fact that there are always examples of the exception to any generality. I've seen the "rules of thumb" broken many times by the "laws of nature".

Again, I think you also are agreeing with me that size alone doesn't matter.

I'm not sure where you're going with your answers. You've inserted conditions such as "not enough water changes" to make my post fit your argument, when it clearly doesn't. I'll bow out and let the science speak for itself.

 

That's what I and everyone else has been saying all along! I don't understand why you seem to feel the need to start new threads as if you have something argue. But you started by saying that tank size is not the limiting factor. Now you're saying that tank size is a catalyst. That's what we've been saying and that's why I keep saying you're splitting hairs! I know there's more detail to the explanation but you keep arguing as if tank size has absolutely nothing whatsoever to do with it. Now you're saying it does. Make up your mind!

 

Why are you twisting my words and obviously getting upset?

By definition, without any other contributing factors, a catalyst has no direct effect. It is only a means to enhance the effect of other factors.

I'm not arguing, It sounds like you are trying to argue but it's not working. Science and physics are amazing. It is not that hard to create conditions that mimic an environment much larger than the actual aquarium that the fish are housed in, therefore negating water conditions or pheromones becoming unsuitable due to size until it becomes an actual physical limitation. All of your statements reinforce what I said in my original post and what I keep repeating. I have not changed up from my original statement.

 

I'm not upset, I'm frustrated from banging my head against the monitor. I'm with hampalong. Bye.

 

Upset, frustrated, it doesn't matter in this context. It's hard to read tone in text. Sorry to see ya all go.

For the rest o' ya all, let's talk about how tank size doesn't matter.

Someone pick a species of fish and we'll figure out how to provide ideal environmental conditions, including minimizing growth pheromones, in the smallest possible enclosure.

 

Sorry Robs I don't think I could help with that theory. I pretty much believe in picking a good tank size, and I try to not to go with the bare minimum for the size. I also don't know much about the growth pheromones, to be of help there.

 

it looks as if your all running in a circle

can you put your theory in a short sentence so I can understand?

 

It's not a theory. Tank size does not cause stunting until it becomes a physical hindrance.

This can be hard to get your head around as can be seen by the conversation above. They thought they were disagreeing with me when their arguments only reinforced what I was saying.

 

so your saying if I put a goldfish in a 5 gallon tank AND keep the water perfect (water changes every day,whatever),it will keep growing until it hits the sides of the tank and then start stunting?

 

Not at all. Please read my first post. It's all covered there.

 

So, tank size alone won't cause stunting until the fish have their movement physically limited. It should be obvious that the fish has outgrown the tank well before that happens. What causes the stunting before that point is reached is poor water conditions or malnourishment.

uhhhh,that's what you said.....

 

Interesting discussion.

If I can summise what I believe is trying to be said.

Up until the point that a fish is physically limited by the confines of the enclosure (tank dimensions), the build up various things in the water can cause/lead to stunting?

If that is the case, and the proposal is that with regular water changes, larger filtration systems etc, that this build can be reduced so as not to trigger stunting (again until physical properties limit the growth).

If that is the case, then is not fair to say that by increasing the water volume, the concentrations are reduced? Keeping in mind that a water change is also a means of dilution of concentrations.

e.g. a 10G with 20G sump/filtration = 30G of water

Therefore, can it not be said that a larger tank holds more water, and thus the concentrations are lower? err go, a larger tank will help prevent stunting, without the need for all the work.

e.g. a 30G tank = the same 30G as a 10G with 20G sump without having a heap of equipment, and extra work.

So in a nutshell, sure, the tank size is not the 'cause' of stunting early on, rather water quality and volume. Larger tank, more water, more manageable parameters = reduced risk of stunting.

 

That's why LFSs are able to overstock all their tanks and put lots of big fish in tanks that would be too small in a home set-up. Take all those tanks on a system, even in a small fish department, add em up and you're quickly into the hundreds of gallons instead of the 20 or 30 that the fish are housed in. That's not even counting the capacity of the filtration system.

Let's look at the water flowing through those tanks. Instead of measuring how much water is filtered per hour like you would for a home system, we are looking at gallons of water changed per hour. Most tanks get the equivalent of several 100% water changes per hour. Of course, it doesn't quite work out to equal the flow of water because there is a dilution factor. so it's really like doing many smaller water changes during that hour.

 

Found this over in the fish ID forum. Posted just yesterday.

Definitely a young Midas/Devil complex. I've seen a true Red Devil at 16 inches, his name was Pinky. My friend did massive water changes every three days, and managed to get him to that size in a 48" 40 gallon tank! The Midevil hybrids are hard to predict, but over a foot is likely.

 

Found this over in the fish ID forum. Posted just yesterday.

But he had room to grow as well....four feet of room.....The fish was not kept in a tank that would inhibit it's ability to reach 16 inches.

I think it is a little bit of both...water quality and tank size. The tank size being more of a factor in extreme situations. Like a fish that is meant to be over a foot growing up in a bowl. It doesn't matter how clean that water is...he will not reach over a foot in something that isn't over a foot in length or width.

But a 4 foot tank gives plenty of space for a fish to reach 16 inches. Maybe not if the water quality was poor. But again...as everyone appears to be saying...it can go either way. The stunting can be caused by poor water quality OR tank size OR the combination of BOTH!!!

What's the debate?

 

As far as I'm concerned, there is no debate, but I'm not sure that others feel the same way. They seem to be using facts that support my statements to contradict what I'm saying and getting frustrated, too. I was hoping this would turn into a discussion about different ways to prevent stunting from water conditions and grow large fish or large quantities of fish in small tanks.

 

Well one way to prevent it is to do more than one water change in 6 months. ;-)

 

I just did that and had zero Nitrates the entire time. It was only after adding more fish that they started to rise. Minimal load and plenty of filtration was all it took.

 

I just did that and had zero Nitrates the entire time. It was only after adding more fish that they started to rise. Minimal load and plenty of filtration was all it took.

I'm sorry but I find that disgusting. Would you want to live in your feces for 6 months straight? Did you at least clean the filters?

 

Robs could you please tell me what you meant by the sentence I quoted from you in post number #27?
I stated the "goldfish in the 5 gallon" thing and you said that's not what you meant,a bit confused here

 

There is no need for name calling, and offending posts have been removed. If it continues, this thread will be closed.

In any hobby, profession and in life, people will always have differing opinions. The difference is in how we handle it. Please be respectful of each other.

 

I reread it a few times and to me it sounds just like what I was saying about the goldfish...maybe I'm just dumb...

You are far from dumb! I think it's confusing for everyone. Lol!

 

More posts have now been deleted.

And with that, thread closed.

 

If a fish has spent significant time in inadequate settings and its stunted, can it grow out some if put into a proper environment?

If those Stress pheromones are no longer being released, can it grow some more?

I imagine it won't be much, but I'm just curious

This question was sparked from another user's rescue post, I just wanted to take care not to hijack their thread.