# WC help fish grow?



## shark (Jan 28, 2009)

Hi a friend told me the more WC you do the faster your fish grow? Has anyone heard of this and is this true? 

Thanks


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## AquariAM (Jan 28, 2010)

Yes. I think this is common knowledge.


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## Zebrapl3co (Mar 29, 2006)

Yes, I agree. This is especially true for pleco. But only up to a point. Think of it this way, if you live is a sucky polluted environment, you will not grow up fit and strong. If that environment is very good, you will grow at an optimal rate. So it's good to make frequent water changes to maintain a healthy environment for your fish. Especially for the fry. But overly doing it won't turn them into giant fish. They will still max out at their genetic limit.

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## Hitch (Apr 26, 2009)

Peter brought up a good point in optimal rate. I personally dont believe that it will make the fish grow "faster" per say, I feel its more like we are providing the environment for them to achieve their natural optimal potential (since even the best setups are still worst than their natural environment).

To my knowledge, some fish (especially fry) will actually release hormones into the environment that suppresses the growth of other fry. Not sure if its true, since I have not read anything scientific on this, but if it is, it does suggest another possible reason for: more WC = faster growth.


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## AquariAM (Jan 28, 2010)

You guys can't be serious. You can double the growth rate on most fish with super frequent water changes. I've got some tang gobies to triple their size a month ago with 48 hour water changes. People can't believe it.


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## shark (Jan 28, 2009)

thanks guys i know its common knowledge..but i just put it out there to confirm


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## KhuliLoachFan (Mar 8, 2008)

Essentially your fish need enough food, to grow quickly, and if fed enough to support maximal growth, you also have to do daily or every-other-day water changes. I don't think that with the SAME amount of food, they will grow faster, with just the water change being the difference. That makes little scientific sense. Fish need food to grow.

W


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## AquariAM (Jan 28, 2010)

KhuliLoachFan said:


> I don't think that with the SAME amount of food, they will grow faster, with just the water change being the difference. That makes little scientific sense.
> W


Does it?

The fish can't grow if it doesn't have low nitrates, abundant trace elements, and generally clean conditions. Also, since many species of fish do release hormones to suppress the growth of their tankmates, frequent water changes remove some of these as well.

Same amount of food, more water changes, a bit more growth. More food, more water changes, a lot more growth. There is such a thing as too much food for many kinds of fish. Many species will grow faster if fed between X and Y amount. Exceed Y and you actually retard growth, likely due to a fatty liver and overworked kidneys.


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## TBemba (Jan 11, 2010)

The perfect example of WC effects on a species read up on Discus. Breeders have been using 50 - 100% WC with many small but frequent feedings during the day. By doing this and selective breeding they have been able to get Discus to grow much larger than they do in the wild. I agree on the effects of fish hormones in the tank. It is very easy to see when growing up fry.


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## Cory (May 2, 2008)

I don't have anything scientific to back this up, only observation, and I haven't done any really controlled testing on this but I don't believe the h20 changes increase the growth rate of the fish in of themselves. In fact, some of the fastest growth I have seen in fry is in tanks which receive very few water changes. I'm just listing some observations here, not saying any of this to contradict anyone who has posted before. I would love to understand it better. 

What I have seen is this:

Fry seem to grow faster in the presence of their parents or at least larger fish. For example, I once accidentally missed a cichlid baby who popped out of her mom's mouth when I was transferring the mother and her tankmate's to another tank. The rest of the babies I raised in a standard setup for my fry with a bare bottom, lots of food and lots of h20 changing. The one baby that got by me ended up in a tank with a bunch of other larger fish that I introduced later and it outgrew all of its siblings by a longshot. Similarly, yellow lab fry spit in my 110 gallon cichlid tank which regularly has nitrates up to 20ppm grow MUCH quicker than those I have raised under controlled conditions.

I've also had experiences where I've sold several fish of the same batch to different people. In the one that received the fewest water changes the fish grew much faster and not only that, in one case, the dirtiest tank of them all, the fish grew to monster size, each one at the max I'd ever seen specimens of the type. 

I also kept a few swordtail fry in a 35 gal planted which received 2 x weekly 30% changes and they have grown so incredibly slowly it's painful. 

Part of me feels like adversity (ie. larger fish, poor water) may trigger a defense mechanism in the form of growth (the bigger you are the badder you are?). I've noticed it also when fish move from one tank to another, they seem to have a sudden growth spurt. 

I've read in TFH that fish grow more rapidly if they are highly concentrated but with pristine water, but have yet to see that in action in my own tanks. 

Has anyone else observed similar?

In answer to the original question though: Whatever effect h20 changes have or dont have on growth there is no way it would work out that you could just keep doing water changes and each time accelerate the growth of the fish. Something like that would have a hard cap where at x point you've optimized the conditions for growth and can do no more.


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## KhuliLoachFan (Mar 8, 2008)

Now it makes sense. Good stuff guys.

W


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## TBemba (Jan 11, 2010)

Fish keeping is a mystery  That is why I love it.

I once had a fish from a Clubs grow out contest (can't remember the fish 15 odd years ago)

I am ashamed to admit it but I put it in a 10 gallon tank with green water so thick you could hardly see the fish and I only occasionally feed him. I took him back to the club before the contest was over because i just didn't have the time for the poor bugger and everyone else that was in the contest asked me how I had got him so big so fast. I think it all depends on the fish the sex the conditions and some mystery that I have yet to figure out.

The more i learn about this hobby, I understand that i do know very little.


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## bae (May 11, 2007)

Bad water conditions will stunt a fish, but even ideal conditions won't make it grow faster or larger than its genetic potential.

But another point is: what are bad or ideal conditions? Green water may look ugly to many, but it's actually quite healthy stuff for most fish. There won't be any ammonia or nitrate, if the algae can pick it up as soon as it forms. Last winter someone posted about buying a large neglected tank overloaded with large cichlids and heavily overgrown with algae. Once visible, the fish looked great -- good health and excellent color!

Algae isn't dirt -- it's really healthy stuff, the more so if the fish will eat it. 

That lone mbuna fry in the big tank had all the microfood it could eat, with no competition from the larger mouthed adults. It may also have had crevices to hide in where it felt secure. There's crowding and there's crowding. Having a lot of cover and hiding places reduces stress even if the only other tankmates are other members of the same batch of fry. Stress reduces health and growth rate. I like to keep a lot of easy weedy plants like najas (guppy grass) and java moss in fry tanks. They remove pollutants (plant nutrients), they provide cover and break up sight lines, making the tank subjectively/psychologically much larger for the fish. They are covered with tiny live edibles, which is not only healthy food, but gives the fry something natural to do with their instincts all day instead of harrassing each other or trying to hide behind each other. In nature, they would try to stay out of sight, and lack of cover stresses them.

These tanks are far from the sterile environments found in hatcheries. For another heresy, mulm is good stuff, like finished compost is good stuff for a garden. It supports a whole ecology of microorganisms as well as feeding the plants. While I have no evidence to support it, note that for any organic compound, there are bacteria that can break it down, so for all I know, they are breaking down those 'crowding' pheromones, and a wide range of other undesirable organics, too. So I'm not fanatic about gravel vacuuming, either. With rooted plants, you don't need to vacuum. Even in fry tanks with unrooted plants, while I change some water, I don't try to remove all the mulm, or keep them squeaky clean.

However, it's impossible to generalize, since fish come from such varied environments. Fish that naturally live in eutrophic environments like swamps, stream banks and shallow still water can really flourish in green water and 'dirty' environments, while fish that are native to almost sterile blackwater streams or other high water purity environments may do best in constantly changed water. Some commercial hatcheries use constant flow systems for such fish, with overall water turniover several times daily. This is probably ideal for discus.

Yet another point is that water changes can be stressful for fish, especially if the incoming water isn't a good match in temperature and other parameters. Large changes can also frighten the fish when the water level drops so far so suddenly, which is an argument for the very frequent small changes most of us don't have the time to bother with. Stress inhibits growth.

Anyhow, I've probably had too much coffee today, and should get back to work!


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## KhuliLoachFan (Mar 8, 2008)

Bottom line: It's complicated. 

I've started keeping notes on what I do, in each tank, and how the fish do. Then I can begin to see what is working for me, and what isn't.

Some fish seem to take forever to get to a size where I can deliver a large enough amount of food to them to start off a real growth spurt. I think that the key is that the tank should contain micro-organisms to give them enough of a start that what I feed them is supplemental.

So far, floating plants seem to be very important hosts to little things that all my fry eat; whether cichlid, livebearer, or otherwise.

W


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## shark (Jan 28, 2009)

WOW!!! I learned alot from this thread


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## Joeee (Apr 3, 2010)

bae said:


> Yet another point is that water changes can be stressful for fish, especially if the incoming water isn't a good match in temperature and other parameters. Large changes can also frighten the fish when the water level drops so far so suddenly, which is an argument for the very frequent small changes most of us don't have the time to bother with. Stress inhibits growth.
> 
> Anyhow, I've probably had too much coffee today, and should get back to work!


If the incoming water isn't a good match in temperature or other parameters, that's just plain irresponsible.

The thing about large water changes that I'm trying out is like drip acclimation, but instead I have one end drinking from a bucket (above the tank) into the tank and another dripping out of the tank. Theorectically, there is little or no stress. Experimentally, there is no change in my fish's behaviour and it is a waste of time. It takes several hours to do a water change.

The thing about change in water parameters and growth may be similar to natural rain. Like how a lot of species of fish spawn when there is a drop in temperature. They may be like how a shrimp releases pheromones externally to signal that they are ready to mate but of course it would just release hormones internally signalling growth.


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## AquariAM (Jan 28, 2010)

Here's the water change thing in a clamshell-  
*
The more similar the incoming water is to the tank water, the larger the water change can be.*

So, if your tap water comes out with a lot of nitrogen bubbles, and you live in a municipality with a lot of chlorine, and you have a lot of peat moss and driftwood in the tank making the pH significantly lower than the tap water, then you have to do a small water change. Maybe 25% at the very most. Even then you'll likely see a tiny little bit of stress.

If you took the tap water, dechlorinated, let it sit overnight, with a heater in it, and a little filter with some peat moss to get the pH about the same, you could do a 60% water change or more and see no stress. Obviously how you do the change matters as well. If you splash a lot, move things around, scare the fish, then they won't enjoy the experience either.


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## Philip.Chan.92 (Apr 25, 2010)

Clean water conditions = healthy fish = healthy rate of growth
Of course you have to take into account a good diet and a lot of other issue but water quality is extremely important.


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## Chris S (Dec 19, 2007)

Joeee said:


> If the incoming water isn't a good match in temperature or other parameters, that's just plain irresponsible.


Just wanted to chime in here regarding this point.

I think there is a degree of misinformation regarding matching temperature (and yes, even other parameters). While it is obvious that an exact match in parameters is the safest method, I can't agree that it is always necessary, nor that it is harmful if done within a reasonable range. For example, having your tank at 30 C and doing a 50% water change with water that is 5 C is not what I am advocating here.

I have two points to make in regards to backing this up:

1. Nature

Sudden rains and dropping temperatures fluctuate the temperatures in waters to a larger degree than many might think. Small creeks and bodies of water also see huge fluctuations in water temperature as the nights get quite chilly, while the days can bring the temperature back up to what many would consider quite high temperatures (30+). A large rainfall into a small body of water can also double or triple the water volume in a very short time during the dry season. While these examples might be extreme (but do happen), there is a lot of flucuation in most natural bodies of water.

2. My own experience

I commonly use temperature differences in my water changes to induce spawning. While these aren't extreme, they are usually around 19/20 C into 26-29 C water. No harm done - in fact the fish respond very positively. These aren't small water changes either - often 50% or more.

Differences in other parameters, such as EC, pH, are also used (also by myself) to promote spawning behaviour. I am a little bit more careful with this though, as to avoid osmotic shock etc.

I guess my point here is that a blanket statement that it is irresponsible to do water changes with different parameters is a bit misleading.

I do agree that unless you have a good sense of your parameters (and have a goal in mind in regards to using different parameters for a water change), then matching is your best bet.


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