Crowding factor, e.g., growth inhibiting hormones

[AvalancheDave]

After many fruitless searches, I finally found evidence to confirm/deny this:

 

[coralbandit]

So why if this was written in 1977 do the smarties still today [well yesterday] say there is no proof of GIH ?
You would really only need to breed swordtails for a year or two to have all the anecdotal evidence you need IMO !
Yea only one big male and then you move him and BOOM !
What do I know ?
Nice article Dave , thanks .
Interesting on the flow through systems they still consider a possible threat or effect for what ever is down stream ..
That would indicate a long life for the hormone or very slow dissolution ?

 

[AvalancheDave]

The hobby is decades behind science and the teaching of science in schools appears to be faltering.

A few hours of research can upend beliefs held for decades.

 

[Mr. Kgnao]

I wish more discussion around specifically this topic were more often informed by a well sourced, empirical article, which reasonably limit its scope, such as this.

Here's hoping people will leave with a more nuanced view of the issue and don't simply say, "Now stunting is science. Superstition is dead, long live superstition."

 

[bizaliz3]

The GIH is in effect in my angelfish grow outs as we speak.

If I remove the runts, they will put on size quickly when removed from the crowd. And my grow outs aren't nearly as crowded as I've seen the grow outs of bigger breeders. But stunting still happens to some.

I've given away runts for free to buyers who wanted them. Its amazing how fast they grow when they are one of only a few in their new tanks. (I love that many of my buyers give me updates on the fish)

 

[AvalancheDave]

I haven't read enough to know if it's in fact a hormone so I really should have stuck with "growth inhibition factors" (the term used in the paper).

There's still plenty of other potential causes of growth inhibition (dominance, diet, and many, many types of parasites) to worry about.

 

[bizaliz3]

I haven't read enough to know if it's in fact a hormone so I really should have stuck with "growth inhibition factors" (the term used in the paper).

There's still plenty of other potential causes of growth inhibition (dominance, diet, and many, many types of parasites) to worry about.

I agree. But the growth inhibiting factors being discussed in the article are to show that those other things you just listed are not the primary and only cause.

Maybe hormone isn't the right word. But it does sound like it was proven to be something chemical related. If I'm reading it correctly.

 

[AvalancheDave]

What happened with past searches is that I'd put in something like "growth inhibiting hormone fish" and get a bunch of papers on hormones inside fish that regulate growth.

Today, I tried that and then wised up and searched for "growth inhibiting hormone fish conspecifics."

 

[Mr. Kgnao]

What happened with past searches is that I'd put in something like "growth inhibiting hormone fish" and get a bunch of papers on hormones inside fish that regulate growth.

Today, I tried that and then wised up and searched for "growth inhibiting hormone fish conspecifics."

On a purely technical level, hormones communicate between systems within an organism, a pheromone is a form of chemical communication across organisms. The inability to distinguish between the two is one of the reasons I'm often skeptical of arguments for chemical based stunting. It's like when you hear someone talk about what the data says, that person ain't no scientist.

 

[david1978]

All I know is fry grow faster with lots of water changes. Why that part I have never been able to test.