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Discussion Starter · #1 ·
as anyone who has ever bred discus will tell you, they benefit greatly from frequent water changes. its pretty much a known fact at this point that if you want to grow discus as fast as possible and get them to their biggest show quality size, you HAVE to change their water often. its not a matter of keeping the water clean, which could be done with heavy filtration and lots of healthy growing plants, it has a lot to do with the hormones that build up in the water, proteins that are released by fish that stunt their growth if they stay in high concentrations.

i have heard of plenty of people who have kept discus successfully in tanks that dont get frequent water changes, but instead have lots of plants. some are successful at breeding them, but what i have never seen is a discus kept in such a tank that reaches the same size as the discus being shown off by people who do massive water changes, or have them on a constant flow system.

this is where my thinking as of late comes into play...
for the last few years, i have been looking into the way ultraviolet light effects water. one thing i noticed is that when i had a UV sterilizer on my tank, my rainbow fish would get a little larger than they did when i didnt have one on the tank. fish that hadnt grown any in the last several months got a little bigger. i think this is because of how destructive UVC is. it got me thinking that if i can squeeze a LOT of UVC into a tank, i may be able to damage the hormones that stunt the fishes growth so that they are, in effect, neutralized.

now, UVC is dangerous to living things. that means that i wouldnt be able to just shove a whole bunch of germicidal bulbs over a tank and call it a day. there is another possibility though... i could set up a sump and put a large, powerful UVC bulb over it. this should maximize the UVC exposure to the water. it would stay in contact with the UVC for longer than it does in a UV sterilizer, even if the overall flow is much higher. plus, i dont have to fry my fish and plants.

i have yet to get any discus, but i do intend to try this, whether it be with discus or another species, maybe a rainbow.

any thoughts?
 

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The hormone thing is bunk, it was a misquote taken out of context by folks before the internet was widespread and is now more "LFS Lore" than anything. I don't know one serious discus person who believes it. It works more like this, the more food you feed the faster a fish will grow, the faster water quality will drop, the more water changes needed.
 

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Not so sure the hormone thing is a bunk, I am friends with a very reputable Discus breeder, who has a couple of books published on the topic of discus an he believes there is some truth to it, whether is a hormone or not we do not know, but the fact that the fish will not reach its maximum potential size in water that is not frequently changed is very true.


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Discussion Starter · #4 ·

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Go over and ask at simplydiscus and come back and report what they say. Again it is a myth that has been passed down the grapevine. If you you search over at simplydiscus you can find where the myth originated from

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The issue with hormones is not a myth and i will stand by that. There just has not been any big research done in the aquarium side to support or disprove the notion.

Do some googling there was a report on a river in the north where fish had steadily been decreasing in size. What they found was an overpopulation due to lack of predatory fish due to over fishing. Why is this important? When they examined the smaller than normal pan fish they found an over abundance of a certain growth hormone in their system which actually created an opposite effect in the fish stunting their growth. So why would this not apply in a fish tank which is a closed eco-system?

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Saying stunting in an overpopulated system is due to GH hormones is cherry picking the research that is out there. Especially in an area where panfish and their predators are selected to be removed by fisherman due to size.

Also this is a bit off topic from the specific "discus anti growth hormone theory" where is goes something like this: Adult discus secrete an anti growth hormone that will cause stunting in other discus so they have less competition. This is the discus myth of lore that is written about in discus books. As far as discus stunting in a fish tank due to GH hormone in the water... Its a neat idea but to claim there is "proof" is silly.
 

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Saying stunting in an overpopulated system is due to GH hormones is cherry picking the research that is out there. Especially in an area where panfish and their predators are selected to be removed by fisherman due to size.

Also this is a bit off topic from the specific "discus anti growth hormone theory" where is goes something like this: Adult discus secrete an anti growth hormone that will cause stunting in other discus so they have less competition. This is the discus myth of lore that is written about in discus books. As far as discus stunting in a fish tank due to GH hormone in the water... Its a neat idea but to claim there is "proof" is silly.
I don't see how it's cherry picking, have you read the article it specifically talks about the growth hormone being something found in the pan fish. It's linking the fact that even in a river system once the population got to a certain the hormones became so concentrated that it is limiting the growth.

Please see link below
http://adventure.howstuffworks.com/...servation/fish-populations/fish-stunting1.htm

As to the proof with discus there is a two way street there. There is no definitive proof to confirm it and likewise there is no definitive proof to deny the claim.

What we do know about discus is that to grow them out you have to do large regular water changes. As to why,i have yet to see any definitive proof as to what the reason is, we must know it has to be done. Some say ammonia, nitrates, yada yada. The weird thing is there is no actual research to my knowledge that has been done on the subject. So until that happens i will stand by that growth hormones / hormones of sorts have effects on fish growth in aquariums not just discus.

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Yes I've read that and its does not mention GH Hormone levels in the water stunting fish. It says external factors can impact hormone blood levels:

"Consequently, a shrunken diet stunts body development. A fish's growth is primary controlled by its GH hormone. The external environment can impact the concentration of GH in a fish's bloodstream, and, therefore, its growth rate. Ironically, stunted fish have more GH released in their bodies than regular fish. However, the stunting also makes them resistant to the hormone, thus limiting their growth [source: Evans]."
 

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Yes I've read that and its does not mention GH Hormone levels in the water stunting fish. It says external factors can impact hormone blood levels:

"Consequently, a shrunken diet stunts body development. A fish's growth is primary controlled by its GH hormone. The external environment can impact the concentration of GH in a fish's bloodstream, and, therefore, its growth rate. Ironically, stunted fish have more GH released in their bodies than regular fish. However, the stunting also makes them resistant to the hormone, thus limiting their growth [source: Evans]."
What the heck you mean it doesn't say that??? Did you read what you quoted right there it says stunted fish have more gh in their body!! The external factor is the fact there is an overpopulation therefore more of the hormone its right there in black and white

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What the heck you mean it doesn't say that??? Did you read what you quoted right there it says stunted fish have more gh in their body!! The external factor is the fact there is an overpopulation therefore more of the hormone its right there in black and white

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Hormones are in their body, produced by their body, not absorbed from the water column.
 

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Ok i see what your getting at... Yes your right, but the stunted fish have a higher gh hormone concentration which is directly attributed to their stunted growth...

So what's encouraging the excessive release, external factors of overpopulation, and who is to say that there is not another hormone released into the water that triggers that? Fact of the matter is hormones can be absorbed and detected externally, thats why i firmly believe there is a limiting hormone that effects aquarium fish that does in fact build up in the water. Which is why water changes are important for growth, to remove those trigger hormones just as much as wastes

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Ok i see what your getting at... Yes your right, but the stunted fish have a higher gh hormone concentration which is directly attributed to their stunted growth...
Yes I agree, this is what the research says and is not a myth.

So what's encouraging the excessive release, external factors of overpopulation, and who is to say that there is not another hormone released into the water that triggers that? Fact of the matter is hormones can be absorbed and detected externally, thats why i firmly believe there is a limiting hormone that effects aquarium fish that does in fact build up in the water.
This is the discus hormone myth/conjecture of discus lore.

Which is why water changes are important for growth, to remove those trigger hormones just as much as wastes
I do 100% changes a day on my discus growout tank.
 

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Would be nice to have a science group do an actual research on it and give us some solid answers!! :)

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Not so sure the hormone thing is a bunk, I am friends with a very reputable Discus breeder, who has a couple of books published on the topic of discus an he believes there is some truth to it, whether is a hormone or not we do not know, but the fact that the fish will not reach its maximum potential size in water that is not frequently changed is very true.


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well, who?
 

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Would be nice to have a science group do an actual research on it and give us some solid answers!! :)

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It would be yes. I believe it was Wattley that first came up with this theory and he was talking about a specific growth retardation substance secreted by the fish not really based on anything other than to try to explain why discus grow better in a tank with large water changes.
 

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I think i remember seeing that excerpt.

Hopefully we didn't derail this thread much.

Auban i hope you got some insight out of this!

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In response to original question....

UV is harmful to living organisms because of it's effect on DNA.
Hormones are not alive and contain no DNA.

Personally, I feel this whole thread contains an awful lot of drawing conclusions without justification.

My example would be diet soda

there is a link between diet soda consumption and obesity. Obese people consume more diet soda per person than non-obese people.

conclusion
1. diet soda makes people obese
2. obese people drink diet soda because they are obese
3. there are other variables at play that have not been explored

My point is simply that knowing two sets of figures does not mean you understand how they related.

As to the hormone question...

If I remember correctly, the stance of most on SD is that the hormone/stunted growth theory has never been proved---so it must be wrong.
But, I believe, it has never been disproved--- so it could well still be a valid theory.

Even the large WC theory has never been PROVED to my knowledge. It is just common knowledge. Of couse it was not that long ago that common knowledge also included the use of leeches to drain the body of 'bad blood.'

Lastly, simply discus is a great site, but it is also very 'cliquey' and those that don't adhere to the 50-100% WC everyday are generally mocked and laughed at and told they will fail. The posters on that site are hobbyists with different levels of education and knowledge and experiences. Most blindly repeat what others post. This does not make them experts.
 

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Discussion Starter · #19 ·
UVC will destroy proteins, if not directly than indirectly as long as it produces something close to 254nm.

ill set up a couple planted ten gallons and a couple groups of rainbows and see what happens. one with UV, one without.

whether its proteins or what not, it will let me know if UV makes a difference.
 

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UVC will destroy proteins, if not directly than indirectly as long as it produces something close to 254nm.

ill set up a couple planted ten gallons and a couple groups of rainbows and see what happens. one with UV, one without.

whether its proteins or what not, it will let me know if UV makes a difference.

THAT is true!
 
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