Does fish growth get stunted in an aquarium?

[vpierce3]

That only works over many, many generations. It happens because the animals live in an environment with limited food and other resources, so staying small is a trait that gets selected for. It may also have to do with epigenetics, but that's another multi-generational process, and is again related to food- not to space. A Great Dane kept in a closet will still grow to Great Dane size, it's just gonna be miserable.

I understand your point. And as I mentioned in another post, it was only an analogy that nature changes and adapts. There are other examples where animals rapidly adapted to changes in environment. A good example are dogs, cats and pigs that go from being domesticated to being feral. Especially pigs that will develop differently physically if thrown into the wild.
I‘m not going to debate how or why….I don’t think anyone has figured that out yet. However some fish remaining smaller in an aquarium is something that many have observed.
When it comes down to it, none of us understand everything about our fish. So it Is impossible for anyone to accurately state their opinion as fact at this point. All we can do is contribute our observations to the discussion.

 

[Randy Holmes-Farley]

With all due respect, OP asked for everyones opinion and experience and that’s what I gave. I understand that you have a different view. And from what I’ve read of you posts, you are very knowledgeable. However I will continue to express myself the best way I can.

I never once said anything negative about your experience. I specifically said I do not know if it happens or not.

What is not an experience of yours is the analogy you gave about evolution to rationalize that the effect happens in other parts of nature and so it seems reasonable to you that it could happen in this setting of a single lifetime. All I did was point out the flaw in the analogy. If you stand by that analogy, fine. You are obviously welcome to that opinion, as I am welcome to point out its flaw.

Others have pointed out the same flaw here, and I see no reason to further discuss it unless you want to.

 

[stephydawn]

My lfs has said similar things before as well. He’s been in the saltwater hobby 30 years. He said he rarely has seen fish reach maximum size they are listed as. He told me it was fine to put a baby sailfin in my 75 gallon and it would likely do well for years. I almost got it but was paranoid after reading tang police posts, haha , so I got the tomini instead.

 

[El Reeflero]

All I can add is this: I've been keeping reef tanks in various forms for decades with at least one clown in every tank. I've literally watched them grow to different sizes based on the size of the tank. Bigger tank...bigger clown!

 

[mmadderom]

This is a confusing topic, especially when dealing with marine life. I have no studies to cite, just knowledge I've acquired while researching various topics during my reefing journey.

In short, no. Do not buy a fish that you don't plan on keeping in an appropriately sized tank. (Buying a young fish with the plan to move it to a larger tank as it grows is fine.) A fish's size is only one factor; its habits are equally important. For example, a marine Betta gets as large as some tangs but is a more sedentary fish. Many other fish need lots of (horizontal) swimming room. Tangs in particular seem to "zoom" around the tank, and they need more space. So a 3-4" bristletooth tang might need a much larger tank than a 6-8" betta.
Some fish are more territorial (like clowns) and can be suitable in smaller tanks than fish that utilize the whole tank. I have clowns that are larger than my wrasse, but while I would be comfortable putting the clowns in a 30 gallon, the wrasse needs a 55+ gallon (standard size) tank. Again, some of it is the dimensions of the tank... standard 75 and 90 gallon tanks are both 48" long x 18" wide, but the 90 is taller; this difference is negligible when it comes to fish needs. But the difference between a 120 (48" long) and 125 (72" long) is much bigger, despite the fact that there only a 5 gallon difference.

The problem with this reply is if you are sizing the tank for a fishes habitat virtually no fish would be appropriate in even the largest home aquarium. Particularly tangs which can swim many miles per day in nature. We think we are replicating our fishes natural environment but reality is we are putting them in prison for our own enjoyment. Obviously my 5 aquariums (including 4 tangs) says I’ve come to terms with this simple fact but we shouldn’t pretend we are doing the animals any favors, either.

 

[mmadderom]

Thanks for the link.

I can certainly believe that there are some deficiencies in aquarium conditions- this is what motivated me to ask the question in the first place. I would love to figure out what is missing - size, chemistry, something else? - and fix it. Also, are some fish more susceptible than others? Finally it raises the question as to whether fish in aquariums are doomed to an unhealthy and stressed life compared to their wild relatives. The above answers seem to suggest this is the case. Which of course would be very troubling. Alternatively, may be it is simple interactions of some harmless chemicals and has no bearing on the health and stress of the fish. Unfortunately it seems like there are few scientific studies that can provide answers.

Unless you can build a mile long aquarium it is impossible to come remotely close to conditions in the wild. That being true it is completely unreasonable to expect life spans in aquaria to match the wild no matter how pristine the water itself is. The only advantage in an aquarium other than readily available food is the elimination of predators. (Says the guy who just had an entire colony of hermit crabs wiped out by a single juvenile puffer)

 

[mmadderom]

All I can add is this: I've been keeping reef tanks in various forms for decades with at least one clown in every tank. I've literally watched them grow to different sizes based on the size of the tank. Bigger tank...bigger clown!

That’s interesting because I bought two equally sized maroon clowns at the same time about a year ago. One in a 16gal other in a 220. The one in the 16 is now almost double the size of the one in the larger tank. The only difference is the one in the 220 gal has a bubble tip while the nano tank has no anemone. I can’t imagine that having anything to do with it, though. Maybe less competition for food in the small tank. All I know is my experience is clearly the tank size itself isn’t an issue in growth rate with these two fish.

 

[Tamberav]

It is probably diet/food related. There is simply less natural grazing area in smaller tanks. A fish can also be fat but being fat doesn't mean all nutritional needs are being met. I would also argue an active fish like a Tang may get less "exercise" in a small tank. Whether that matters or not.. idk.

I suppose maybe a small environment causes some sort of chronic stress as well...

I doubt stunting of fish that are from an area as large as the OCEAN... is anything that should occur naturally in a healthy fish. Fish are supposed to grow and breed/reproduce and survive. A stunted fish in the wild is probably fish food.

The goldfish thing.. I don't know gold fish but the same websites that say hormones stunt goldfish also say it is harmful to their immune system. If so, I would not call that healthy.

 

[vpierce3]

I never once said anything negative about your experience. I specifically said I do not know if it happens or not.

What is not an experience of yours is the analogy you gave about evolution to rationalize that the effect happens in other parts of nature and so it seems reasonable to you that it could happen in this setting of a single lifetime. All I did was point out the flaw in the analogy. If you stand by that analogy, fine. You are obviously welcome to that opinion, as I am welcome to point out its flaw.

Others have pointed out the same flaw here, and I see no reason to further discuss it unless you want to.

First of all, nowhere in my post did I mention evolution. Nor did I speak about time-line or any underlying mechanisms for changes noted. As for my mention of the animals on the Galápagos Islands, there is no proof whatsoever that evolution is what drove those animals to change. Nor is there any record of how long it took. It’s interesting to note that even Darwin himself admitted he came to the wrong conclusions later in life. My analogy demonstrates that change is possible…..period…..full stop. It wasn’t me that inserted the subject or timeline of evolution in the conversation. That was implied by others.
I also expanded on my explanation by bringing out how domesticated animals can change (even physically) when their surroundings change.
Even we as humans change based upon our environment and living conditions. Our bone structure, our vision, our growth, the pigment in our skin, our metabolism, and the list goes on. I see no reason why some similar unknown process might affect the growth of fish in a confined environment.
So, instead of assuming what the ‘rational’ behind my analogy is, it would have been more propitious and gracious to simply state you disagree instead of calling it flawed.

 

[Stigigemla]

Fish are different. Some fishes grow much bigger in aquariums then in nature.
Other fishes get smaller in tanks.
Chromis virides often gets 11 cm in tanks but that size does not exist in nature.
I have had a mandarin fish of 11 cm too.
I just measured a dead Cirrhilabrus naokoae to 14,5 cm. Generally it is sold as reaching max 10 cm.
Other fishes dont grow that big. Tangs usually are smaller in tanks but we often do wrong when talking about sizes. Females of some species are smaller and we cant expect them to grow to male sizes.
I read somewhere that yellow tang females were 2 - 3 cm smaller than the males in nature.
Other tangs seem to be of similar size when looking on pairs in all the reef movies in the net.

 

[Groovyd]

Yeah, as mentioned this is a really complicated topic because there are so many variables that go into it, so studying it in such a way as to have the findings be useful/meaningful for mutliple species would be incredibly time consuming (and there would likely be numerous potentially confounding variables for any mixed-species setups like the typical reef tank).

*For an example of a confounding variable, two different fish species might not show any stunted growth when kept by themselves, but then show stunted growth when kept together. In a situation like that, it could be a chemical put out by the other species inhibits the other’s growth, it could be caused by an interaction between chemicals put out by the two species, it could be a stress response, a response to aggression, a response to food competition, an attempt to appear less threatening, etc. (On the other side of this example, two fish species may show stunted growth when kept separately, but not together - this is, again, a whole can of confounding variable worms.)

With regards to fish in aquariums being “doomed to an unhealthy and stressed life,” I wouldn’t necessarily make that assumption. Just because a fish doesn’t grow to its maximum wild size doesn’t mean it’s unhappy (or even stressed at all). While that assumption is (to my knowledge) entirely possible, there are also a number of different possible explanations for the difference in growth (including, in addition to the possibilities listed above - though arguably unlikely - that the fish grow bigger in bigger tanks because they feel they need to in order to survive or increase their odds of survival; in other words, it’s possible- albeit unlikely- that they grow bigger in response to specific stressors::::similarly, the fish might stay small in smaller tanks because of some advantages it provides - such as requiring less food, as food would [at least theoretically in the fish’s mind] be less abundant because of the small available space for food to grow/hide).

Regardless though, I’d honestly assume the general health and happiness of the fish probably depends less on tank size (though I certainly believe it plays an extremely important role) and more on the care given them by the aquarist. A proper size of tank and proper care would likely provide a good quality, safe, stress-free, happy life for a fish. As was mentioned above, however, many people can’t keep their fish alive for a decent length of time (and fish that die young were probably pretty stressed).

Personally - disease aside - I’d guess a lot of premature fish deaths are largely because of improper diet (speaking candidly here, the more I learn about pet nutrition and pet food - and not just with fish - the more I realize that most pet foods, while possibly good enough to keep a pet alive for a while, are not good enough to keep a pet healthy/in peak physical condition long-term) and improper care (be it through poor water quality, bad tankmates, improper habitat, etc.). When you have proper care and proper diet, the fish live for long times (in some/many cases matching or exceeding their wild lifespans) and are happy enough to reproduce readily and exhibit their natural, wild behaviors. So, personally, I’d guess those fish are quite happy and content with their lives.

 

[Groovyd]

Interested in offering the best diet to promote healthy , long lived fish. You mentioned not all aquarium food being adequate for stress free fish. I am an 18 month newby, my husband is the scientist. Loving advice.

 

[Jay Hemdal]

Fish show indeterminant growth to a greater or lesser degree, depending on species. Small, tropical species do not show it at all. "Stunting" due to captivity is also variable. Pacu don't seem to stunt at all, while Lake Victorian cichlids do.

The maximum size that fish will grow in aquarium can be estimated. This can be done by looking up its listing at www.fishbase.org There will be a value given for the maximum recorded length for that species in the wild. An informal study at one public aquarium showed that on average, long term captive fish typical of those housed in home aquariums only reached 66 to 75% of the maximum length for that species listed on FishBase. Therefore, multiplying the given maximum length by 0.75 will give a reasonable estimate of how large that species will grow in an aquarium.

Jay

 

[Randy Holmes-Farley]

First of all, nowhere in my post did I mention evolution. Nor did I speak about time-line or any underlying mechanisms for changes noted. As for my mention of the animals on the Galápagos Islands, there is no proof whatsoever that evolution is what drove those animals to change. Nor is there any record of how long it took. It’s interesting to note that even Darwin himself admitted he came to the wrong conclusions later in life. My analogy demonstrates that change is possible…..period…..full stop. It wasn’t me that inserted the subject or timeline of evolution in the conversation. That was implied by others.
I also expanded on my explanation by bringing out how domesticated animals can change (even physically) when their surroundings change.
Even we as humans change based upon our environment and living conditions. Our bone structure, our vision, our growth, the pigment in our skin, our metabolism, and the list goes on. I see no reason why some similar unknown process might affect the growth of fish in a confined environment.
So, instead of assuming what the ‘rational’ behind my analogy is, it would have been more propitious and gracious to simply state you disagree instead of calling it flawed.

if you believe differences displayed by animals in the Galapagos may have been generated within a single animal lifetime by adapting each single animal to the local conditions, as opposed to adaptation over many generations by natural selection, then we do not have a shared vision of the natural world and I’m not going to waste REEF2REEF readers time trying to convince you.

 

[Randy Holmes-Farley]

Fish show indeterminant growth to a greater or lesser degree, depending on species. Small, tropical species do not show it at all. "Stunting" due to captivity is also variable. Pacu don't seem to stunt at all, while Lake Victorian cichlids do.

The maximum size that fish will grow in aquarium can be estimated. This can be done by looking up its listing at www.fishbase.org There will be a value given for the maximum recorded length for that species in the wild. An informal study at one public aquarium showed that on average, long term captive fish typical of those housed in home aquariums only reached 66 to 75% of the maximum length for that species listed on FishBase. Therefore, multiplying the given maximum length by 0.75 will give a reasonable estimate of how large that species will grow in an aquarium.

Jay

Thanks Jay.
Do you have an expectation for the reason(s) why?

 

[Jay Hemdal]

Thanks Jay.
Do you have an expectation for the reason(s) why?

Sorry, not even a wild guess!

Jay

 

[Jay Hemdal]

Fish are different. Some fishes grow much bigger in aquariums then in nature.
Other fishes get smaller in tanks.
Chromis virides often gets 11 cm in tanks but that size does not exist in nature.
I have had a mandarin fish of 11 cm too.
I just measured a dead Cirrhilabrus naokoae to 14,5 cm. Generally it is sold as reaching max 10 cm.
Other fishes dont grow that big. Tangs usually are smaller in tanks but we often do wrong when talking about sizes. Females of some species are smaller and we cant expect them to grow to male sizes.
I read somewhere that yellow tang females were 2 - 3 cm smaller than the males in nature.
Other tangs seem to be of similar size when looking on pairs in all the reef movies in the net.

I've noticed that the "aquarium giants" are often a one-off. You've seen a 11 cm green chromis, but I have a shoal of 6+ year old ones that have maxed out at <8 cm in a 8000 l reef. I once had a person bring in a royal gramma that was over 20 cm, I've never had one grow larger than 12 cm. I have had one male mandarin reach about 11 cm.

Two issues confound fish length measurements: people are really poor at estimating the size of fish in aquariums, the water magnifies everything by 30%. Then, some people use total length and others (fish taxonomists mostly) use standard length (without the tail). Measuring fish directly, like you did with the dead wrasse is most accurate. Because I'm a diver and have worked with aquariums all my life, I tend to unconsciously deduct that 30% magnification, so my size estimates tend to be less than many people's.

Jay

 

[fish farmer]

Fish show indeterminant growth to a greater or lesser degree, depending on species. Small, tropical species do not show it at all. "Stunting" due to captivity is also variable. Pacu don't seem to stunt at all, while Lake Victorian cichlids do.

The maximum size that fish will grow in aquarium can be estimated. This can be done by looking up its listing at www.fishbase.org There will be a value given for the maximum recorded length for that species in the wild. An informal study at one public aquarium showed that on average, long term captive fish typical of those housed in home aquariums only reached 66 to 75% of the maximum length for that species listed on FishBase. Therefore, multiplying the given maximum length by 0.75 will give a reasonable estimate of how large that species will grow in an aquarium.

Jay

I tend to look at the maximum size in the wild as being an outlier or possibly a recording of a strain of bigger fish.

I work with salmonids so I typed in brown trout.

The maximum recorded age is 38 years. Maximum length is 55 inches. Max weight is 110 lbs. That's a big brown, not sure if it is a recording of one sea run strain that is long lived or a hundred fish that were sampled in various locations. The world record caught on a line is around 44 lbs.

The common length is 28 inches, maturity is 16 inches, which makes more sense with what I've seen with cultured browns and wild fish. The strain that I raise seemed to be able to reach 15 to 20 lbs. in the wild and culture conditions, but spawning stress takes it's toll when they reach sexual maturity, so the big ones we've had on station are a rarity.

 

[Malcontent]

I have the opposite experience.Fish look small to me in the tank but huge when I net them and take them out of the water.

 

[Randy Holmes-Farley]

I have the opposite experience.Fish look small to me in the tank but huge when I net them and take them out of the water.

I’ll bet the ones that get away look especially huge! lol