Fish growth hormones

[aqua_chem]

One problem I see here is that these problems are often confounded to the point that you can really draw any conclusions. Let's say that you have an oscar in a 30g, which I'm sure we can all agree is inappropriate. If the fish stunts, what caused it? I feel that many aquarists put undue emphasis on tank size and not on other, more difficult to quantify contributors. For instance, I don't see someone that puts an Oscar in a 30g tank providing a nutritious and varied diet, which is in my mind a stronger reason to cause stunting; similarly, tank maintenance is probably not up to snuff either.


For the record, I think that the idea of fish hormones stunting growth is likely bunk.

 

[Delapool]

For the record, I think that the idea of fish hormones stunting growth is likely bunk.

Could you expand on why here? Just curious. Is it not possible at all or are fish hormones just part of it?

 

[aqua_chem]

Could you expand on why here? Just curious. Is it not possible at all or are fish hormones just part of it?

It certainly possible, but A) it seems counterintuitive to me and B) I'm don't think I've ever read anything that suggests that this is even the case.

On the counterintuitive point, the majority of hormones are growth inducing or growth neutral, to the point that the aquaculture industries actively adds many hormones (or has investigated it) to their pens to induce growth. While it's possible that some hormones could stunt growth, such as cortisol, it seems odd as it is primarily a endocrine hormone rather than exocrine and would have to somehow find its way unaltered from blood to external environment, then back again into blood, to have an impact, and even then it would have to be at high enough levels to overcome the pituitary's regulatory functions. There's a good number of leaps of faith in that argument that I'm not willing to buy without stronger research on the matter.

That's not to say that endogenous cortisol won't run amok with a fish's growth, which is a strong possibility. I just don't see it happening through exogenous mechanisms.

 

[BillD]

There are numerous factors that will influence the growth rate and eventual size of a fish. firstly, clean water is essential to rapid growth. Secondly is quality food and the amount fed will dictate growth rate where water quality isn't an issue. From scientific studies, it has been determined that reducing a fish's diet by 70% from optimal will still result in growth. The growth of course will be much slower. Another factor is temperature. Keep fish at a lower temp and they will generally grow more slowly. They generally will live longer as well. In my experience, live bearers such as guppies will live about a year longer in unheated tanks as opposed to those kept around 80F for rapid growth. they will grow more slowly but still reach their maximum size. When Stan Shubel spoke at the CAOAC convention about 10 years ago, he stated is 10 gal grow out tanks for mails contained 80 fish. these are very expensive fish because of the quality. Clearly he would not jeopardize his reputation or sales by doing things in a haphazard fashion. Most would say those tanks were over crowded.
My (limited) experience with raising angels is that you can achieve very good growth rates in very crowded conditions (300 in a 30) if you keep the water clean and feed lots of food. The caveat here is if you feed lots, you need to increase the maintenance accordingly. In my case it was 70% daily water changes.

 

[aqua_chem]

My (limited) experience with raising angels is that you can achieve very good growth rates in very crowded conditions (300 in a 30) if you keep the water clean and feed lots of food. The caveat here is if you feed lots, you need to increase the maintenance accordingly. In my case it was 70% daily water changes.

I buy this 100%, coupled with the fact that many breeders are using higher quality food as well.

 

[jetajockey]

Found an interesting article that cites sources just a lil bit ago, figured I'd share it.

Do fish grow to the size of their tank? - INJAFINJAF

 

[jlk]

Found an interesting article that cites sources just a lil bit ago, figured I'd share it.

Do fish grow to the size of their tank? - INJAFINJAF

Great article, Jeta! As I mentioned briefly earlier in this thread, it's well known within the goldfish community that hormones play a big role in goldfish growth (in addition to diet and water quality) and huge, frequent water changes are the accepted norm for optimal growth. The research I have read on hormones and their affects on growth have been mainly focused on Cassius auratus but I have also read some interesting studies on wild fish populations as well.


Sent from my iPhone using Aquarium Advice

 

[aqua_chem]

Can you post one of those sources? We often view things as 'well known' when they are in fact 'generally accepted' and not based in much solidly at all, e.g. the long held thought that phosphates cause algae in FW tanks.


Sent from my iPad using Aquarium Advice

 

[Mebbid]

Can you post one of those sources? We often view things as 'well known' when they are in fact 'generally accepted' and not based in much solidly at all, e.g. the long held thought that phosphates cause algae in FW tanks.


Sent from my iPad using Aquarium Advice

I'm curious myself. Also, thank you for the phosphate comment Not enough people listen to me when I say it.

 

[Joeybsmooth]

I started out this hobby my keeping turtles , and I was following the same mind set that a smaller tank would = a smaller turtle becuase some how there bodies know not to grow. However that is not the case with turtles and I can suggest that is not the same with fish . When we keep these animals in tanks that are two small , they stay small not becuase their body doesn't want to grow but becuase of the water quality . I know you might LOVE your animals but there is a reason that there are sized recommendations .