# What makes our fish grow and can we grow them too fast?



## Warhawk77 (Jan 8, 2014)

I was thinking about this last night and wanted to share the idea with others to see if anyone else has thought about this.

On this site and others people often ask how to make their fish grow faster and we normally tell them the same thing there are 3 basic factors that effect fish growth. Food, Water changes, and Genetics. But there is anothor factor often over looked but I have read many people do it, Metabolism.

We have all bought fish that never got as big as we thought they would, this could be for many reasons but I think growing fry too quick effects the fish in the long term.

*Food*
We all know Food is a big factor in fish growth but you have to make sure the fish gets the nutrients from the food or you are wasting it. That is why I feed 2-3 small meals every day, fish have a short digestive track so feeding small amounts many times keeps food in the system longer and give them more time to pull the nutrients from it.

*Water changes*
Doing lots of water changes as long as you keep the cycle going in the tank shouldn't cause any issue with the fish. The fish release chemicals in the water that cause other fish to not grow as fast(no idea what they are) so you need to keep changing the water to keep those chemical levels low. Along with this you have tank space, if the tank is too small it will stunt the growth and too large makes it hard for small fish to find food. That is why many people have fry and grow out tanks.

*Genetics*
Not much we can do here some fish grow faster than others. The size of the parents will effect the size of the fish also so if you want large fish find the breeder with the largest fish. Also inbreeding can stunt fish along with lots of other harmful things.

*Metabolism*
A key factor with how much nutrient fish get from the food is the fishes metabolism, if it is higher it will help process the food faster and cause them to grow faster. *I DON"T DO THIS AND DON"T RECOMMEND IT TO ANYONE!! * If you raise the water temp it will raise the metabolism of the fish, gold fish are cold water fish (65-75F) and their growth rate is pretty slow because they live for many years. Fish that come from warmer waters tend to grow faster but don't live as long and this is because of the metabolism being higher. Betta for example often die in 3-4 years because the water temperatures are much higher.

This has caused me to believe that if you keep fish are a warmer temperature it shortens their over all lift span because you are raising their metabolism. How much this really effects the fish I don't know. I also understand genetics are different in gold fish and betta and that makes a big difference in lift span, so that isn't a good comparison. If someone had time and space they could test this with splitting a group of fry into two different tanks one that is heated more then the other and allow them to grow out and see which group lives longer.

So what do you guys think can you grow fish too fast?
Does growing them fast harm the fish or shorten the life span or have any other long term effects?

My goal is to have a conversation about this topic, I really enjoy keeping fish and all the small aspects of the hobby. I'm sure we all want to keep the healthiest fish we can and enjoy them for as long as we can.


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## tanker3 (May 18, 2015)

Nice post. I agree with most of this post, except
"fish release chemicals in the water that cause other fish to not grow as fast"-- Not sure how true this may be, I know plants do this, but fish? I think in the wild, with so much water flow, that any chemical that is released will be too diluted to have any effect on neighboring fishes.
Warm water does increase metabolism, but how it effects the fish health in the "long run", not sure. Discus and Rams for instance like their temps higher. Does this shorten their life? I do not know. When I use to raise guppys I would raise the temp so that the guppys would grow faster, but I did not record their life span in contrast to those that was raised in lower temps. I just knew they grew faster.


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## Warhawk77 (Jan 8, 2014)

I can't prove the release of chemicals but I have read it from different sources. In the wild the water flow will remove those but in the aquarium it builds up.

It would be nice to know if higher temp do effect life span but short of testing it with 2 tanks no way to be sire. Would also have to do a few fish because some times they just die.

Thanks for feedback. Maybe others can tell us for sure, I'm just a guy keeping fish not a expert.


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## tanker3 (May 18, 2015)

Warhawk77 said:


> Maybe others can tell us for sure, I'm just a guy keeping fish not a expert.


Me too, but nice post. Let's hear from others.


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## Aaron S (Apr 4, 2015)

One small thing to add. Food has two important quantities that give rise to a sub category which is dominance. If you have 5 fish and throw in 5 grams of food, I guarantee that each fish will not eat 1 gram. Often the most dominant fish will be the most aggressive at eating and will get more food thus affording more nutrients and that is why they often become the largest fish (barring genetic issues).


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## DJRansome (Oct 29, 2005)

I agree with Aaron. Dominance is a factor out of our control and clean water is the biggest thing within our control. I'm assuming everyone feeds good quality food sufficient to keep the bellies from becoming concave.

I do think that fish that are power fed and kept at higher temps to grow them faster become poorly shaped and sized adults.

At this moment in time I think the idea that fish release chemicals to inhibit growth in a crowded tank is believed to be a myth or at least not proven as generally applicable to all aquarium fish.


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## Warhawk77 (Jan 8, 2014)

DJRansome said:


> I agree with Aaron. Dominance is a factor out of our control and clean water is the biggest thing within our control. I'm assuming everyone feeds good quality food sufficient to keep the bellies from becoming concave.
> 
> I do think that fish that are power fed and kept at higher temps to grow them faster become poorly shaped and sized adults.
> 
> At this moment in time I think the idea that fish release chemicals to inhibit growth in a crowded tank is believed to be a myth or at least not proven as generally applicable to all aquarium fish.


I agree with Aaron too. I'm sure every tries to spread the food around so everyone gets some but yes bigger fish will get the most. In a breeder setup the largest fish would be moved to the larger tank to be with others the same size to help keep the one fish from dominate the whole tank of small fish.

I agree with DJRansome here about the poorly shaped adults

On the release of chemicals I was reading online last night about that. The books (10 years old) I have list that as a fact but it does look like people are disproving that or at least starting to question it. Who knows maybe in a few more years it will be proven false like many other things from the hobby. This is one of the things I like about the hobby it is always changing because people are learning new stuff all the time.


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