Organs keep growing when stunted?

[reptileguy2727]

Is there absolutely any evidence at all for this?

I see it mentioned frequently, especially with big cichlids in reference to minimum tank sizes. People say the internal organs will keep growing when the fish is stunted, eventually causing problems and death. From a biology point of view this does not make sense. Cells and tissues naturally stop growing when they fill the space they are in unless they are cancerous. So what would make it an exception in fish in an aquarium?

[trashion]

I've seen it happen to fish. My friend kept a goldfish in a 10 gallon tank, it lived for five years. And it ceased growing, but it began to bulge out in strange ways.

[reptileguy2727]

How wdid it grow in weird ways?
How do you know it was the organs?

I have seen many stop growing in length and put on gurth. Anyone ever cut one open and compared the organs of a dead stunted fish to that of a dead fish that was not stunted?

[Star_Rider]

what of the eye's? they are organs and they are larger than the bodysize of the stunted fish and are a typical indicator of stunting.

some research also indicated curved spines in stunted fish..is this possibly caused by displacement of the organs outward causgint the deformation?

[trashion]

Yeah, the eye thing I know from experience. I had a skirt tetra that survived 3 years of poor fishkeeping, and he definitely stunted. He was not full length by any means, and he was five years old when I traded him to my LFS. However, his eyes were BIG. Much bigger than his mouth, almost even the size of his fins.

[Coler]

There are different 'types' of stunting. for instance, take a goldfish and put it in a 55 Gallon, underfeed it. It will not achieve what is considered proper growth, and is therefore stunted. It will appear emaciated, be vulnerable to disease and be unhealthy. If this is not corrected in time, and occurs from a young age, the fish although fed well for the rest of its life will like always carry the physical consequences, like a malnourished human child. Its growth rate throughout its mass may not be even, giving it the appearance of lumpy deformity.

Take a fish which is kept in a cramped tank leaving it no room to maneuvre normally; this can result in skeletal deformities, which will inhibit growth, but not prevent it, and impact on internal organs. this is probably closest to the classic perception of what stunting is and while it is not necessarily that the fish stops growing its skeleton while continuing to develop its internal organs, it is somewhat close, in that the deformed skeleton arising form cramped conditions impacts negatively on development/performance of internal organs, often swim bladder.

take fish which are kept overstocked and underfiltered. the release of growth inhibitor hormones by dominant fish will inhibit growth, and again lead to stunting of physical size, but as long as sufficient food is eaten, there being no skeletal abnormality, the fish may not appear deformed except in size. the underfiltering will of course impact on health in other ways.

your classic Oscar in a 20G for life kept by someone who doesn't know better is probably going to be overfed, so big bulgy belly, underfiltered and insufficient water changes, so disease problems from this, and if achieving any real size may encounter the skeletal deformities...hence the 'stunted' fish.

There is a real difficulty in isolating the cause of the illness and deformities in a stunted fish because there are a) different causes of stunting and b) stunting will only over occur to a fish which is being raised in a poor environment and this will in and of itself cause problems.

The 'Organs keep growing when stunted' hypothesis is not in my opinion 'mythbusted' but is an over simplified way of describing symptoms/deformities often present in 'stunted' fish. An in a 'classically' stunted fish, is pretty much close enough to the reality for most people.

Think about a corrollary of the 'Organs do not continue growing' theory - that would be the 'fish grow to fit the size of the tank' theory. Neither is entirely true (the latter is an evil half-truth), neither is entirely untrue.

edit :^ all of this entirely my own surmisal and opinions of course, and not in the least bit backed up by any scientific evidence.

[Star_Rider]

I'm not sure if there is truth to the internal organs issue tho.

but keep in mind that the area the internal organs are in is designed to 'flex'

I think there ore other significant issues to be concerned with as the cause of stunting is also attributed to other health issues related to organs that don't function correctly.

[reptileguy2727]

If it was true then fish kept under conditions that produce certain types of stunting would have this happen repeatedly and on a more regular basis. I have not seen this. There may be a few tetras, a couple oscars, etc. that display certain characteristics like larger than normal eyes or a bulging belly (can also be caused by a prolonged incorrect diet which would almost be expected if someone is taking improper care of their fish), but with it being so inconsistent and relatively very rare I do not think it shows any trends.

Either way avoid stunting at all costs.

[pinkertd]

There are different 'types' of stunting. for instance, take a goldfish and put it in a 55 Gallon, underfeed it. It will not achieve what is considered proper growth, and is therefore stunted. It will appear emaciated, be vulnerable to disease and be unhealthy. If this is not corrected in time, and occurs from a young age, the fish although fed well for the rest of its life will like always carry the physical consequences, like a malnourished human child. Its growth rate throughout its mass may not be even, giving it the appearance of lumpy deformity.

Hey Color, I think you hit the nail on the head. I never thought about it this way before, but the conditions we would subject a fish to would have similarities to conditions we subject a human too. I think it's pretty much bunk that the organs continue to grow bigger than the body cavity can accomodate. They will be undersized or sized for the body that contains them. I can relate to you about one of my sons. One of my very premature triplet sons was born with a congenital birth defect, tracheo-esophogeal fistula. That in itself is easy to fix in a full term baby, but not so easy in a 2 lb baby. We encountered a series of problems along the way, all starting with the TEF and him having to be fed with a G-tube in the stomach. One problem created another until I could barely keep any food in him. He came home after 4 months in the hospital weighing 7 pounds. At 12 months of age he was still only 10 pounds and close to dying from failure to thrive. Those 12 months of improper nourishment to his body have had and continue to have an effect on his normal growth rate and physical development even at the age now of 16 1/2 years old. One of my triplets is 6'1", the second is 5"11. James is now 5'4" and weighs a mere 90 lbs. Puberty has been delayed, teeth had to be pulled since his jaw was too small to accomodate all of them, and his internal organs are all sized for the body he has now. His organs did not continue to grow too big within his small frame. How could it possibly be any different for a fish...or a dog....or a cat for that matter. They would be like my son. And if you contained a human child in a too small place to live like you do with a fish, there could be other physical deformities from lack of being able to move properly and use muscles and appendages properly. And if you put shoes that are way too small on a childs growing feet, those feet will not grow normally, there will be some sort of deformity resulting. You could compare that to a tank too small for a fish to turn around in. And if you gave a human child filthy conditions to live in, they would be more sickly....same as a fish. Proper food for the entire time of development and growth, proper environment and room to grow.....all living things develop normally when provided with enough of these.

[Coler]

If it was true then fish kept under conditions that produce certain types of stunting would have this happen repeatedly and on a more regular basis. I have not seen this. There may be a few tetras, a couple oscars, etc. that display certain characteristics like larger than normal eyes or a bulging belly

a few tetras ? a couple Oscars ? I don't know why it would be limited to those numbers and those species.

underfed fed = small, not 'average' growth for species = stunted

fish kept in high nitrate environment = small, not 'average' growth = stunted

fish kept in underfiltered overstocked environment (nitrate plus growth hormone inhibitors) = small, not 'average' growth = stunted

fish kept in tiny aquarium, not sufficiently large for size of fish = I don't know what to call this, but lets say stunted and we'll all know where we are.

'stunted' is neither a term of art nor a scientific description

[reptileguy2727]

Not that few fish are stunted, but that relatively so few of the stunted fish exhibit the traits that are considered to be a symptom of a far from proven theory of organs keep growing even if the fish stops. Not to mention that most of these traits have other causes that are not ruled out, poor diet being one thing that can cause many of these issues, not necessarily their organs growing beyond their internal limits.

[Star_Rider]

there is research that consistently shows the issue with large eyes on stunted fish. the eye's continue to grow regarless of the cause of stunting.. keep in mind that the organs will get most of the nutrients when consumes..the muscle and skeletons show the earliest signs of malnutrition. in cases where stunting may be caused by lack of food.
check wildlife studies regarding stunting in ponds etc.
they eyes will continue to the adult size or the relative size of the species at the given age of an otherwise healthy fish.
reptileguy..the eyes are organs...if you are referring to internal organs malnutrition is one cause of stunting but not the sole contributor.

coler is correct there are other factors..carrying capacity I believe is a better term when considering stunting etc.

[Coler]

Think about a corrollary of the 'Organs do not continue growing' theory - that would be the 'fish grow to fit the size of the tank' theory. Neither is entirely true (the latter is an evil half-truth), neither is entirely untrue.


I would amend the last word to 'accurate' and leave it at that

[reptileguy2727]

Do you have any links to these studies?

Even then I have not come across many stunted fish that have abnormally large eyes. Those may also be one exception because they are internal. If they keep growing they do not hit a body wall or other organs, they simply grow farther out of the head. So the space limitation is not really at work there.

[Star_Rider]

no links these are docs at the library (WSU)

I actually studied similar docs at WSU when I was getting my BS in forestry.
you see in Forestry we had to consider the impacts of timber harvest. which directly affect the carrying capacity of the land. long term and short term(not all bad btw)
had to do a stint and studies re Wildlife and carrying capacity.
impact of wildlife in habitats.

[Star_Rider]

you may have to do research at a University Library.

I did all my research there when getting my BS Forestry..btw I had to study the impacts of timber harvest on the ecosystem.
you may also want to quiz some of the 'experts' ar some of the Discus forums too
but we must keep in mind that large eyes are not the sole indicator of stunting and may also be attributed to other abnormalities.(gentic and or environmental)

you may also want to quiz area fisherman..I have personally seen stunted trout..their heads are typically abnormally large in regards to thei body size..but then again as pointed out what is the root cause of this stunting. there are many variables that are related to stunting.

more importantly what are the effects of 'stunting'.

a malfunctioning liver may enlarge..but is it a result of environental issues which may be part of stunting?

[reptileguy2727]

Good thing I am a bio major at GMU. Remember what journals?

That is one of my points too, large eyes don't necessarily mean they are stunted.

It is just something I have seen repeated a lot with effectively no or at best very little hard evidence for.

[Rbishop]

I think some organs are genetically predestined to be a certain size; it may be below, at or above normal, for a given species. The environment the fish is kept in can affect that growth, from a nutritional standpoint, from developing correctly to the code imbedded in the cells.

The environment can also affect proper development of the skeleton and skin tissue.

I can easily correlate the poor water conditions setting up for a small skeletal frame and organs trying to reach normal size, which, IMO, would cause some very distorted fish.

[pinkertd]

Here is some excellent reading on the explantion of eye size and discus and why some are different.
http://forum.simplydiscus.com/showthread.php?t=49201

[Coler]

It is just something I have seen repeated a lot with effectively no or at best very little hard evidence for.

I believe the point to the replies to this thread it is perhaps that no one is going to advocate keeping fish in conditions likely to stunt them on the basis that there is effectively no or at best very little hard evidence that their organs will continue to grow while their skeleton does not.