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GIS: Growth Inhibiting Substances, do they exist?


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Many refer it to it as hormones but I believe that is incorrect. So far there hasn't been any scientific evidence to point towards a specific chemical compound whether released from the fry or not.

But, what is everyone's opinions on this matter (Continuing this topic on from facebook). Who here believes it exists?

As far as I've noticed, the larger, more frequent water changes that are performed the more uniformly and faster the fry seem to grow. Guess its time to see everyone else's opinion. :)

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Just thought of a way that could test the theory.

All you would need is a barracks system that allows only one way flow of water from one chamber to the next.

the first chamber gets fresh water at a very slow, constant rate. The water then needs to flow out to the next chamber at the same rate as it goes in to the first. The second chamber flows out into the third at the same rate and so on etc etc. The last chamber flows out to a waste water system/down sink.

If growth inhibiting substances exist, then the fish in the first chamber will always grow fastest despite equal food rations. The one in the last will always grow slowest. The term "fastest" and "slowest" would need to be average growth rates over several trials so that random error is minimised.

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Thats a very interesting idea. If you built a custom system with a drip that goes does each level. Making sure that each container has the same amount of water and essentially drips into the next the whole way down.

Would be an expensive experiment to design and create, especially since you'll need at least 15 fish to make it a decent test.

I'm half tempted of jarring out half of one of my spawns early and doing the same percentage of water changing and seeing the results.

It could just be the best growing is the best eater, but I think there is something more complex going on that forces fish that eat very well to not grow compared to other fish from the same spawn.

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From a hobbyist perspective I suppose it doesn't really matter what actually inhibits the growth we're more interested in what encourages growth. Although if we knew for sure it was something chemical perhaps carbon or some other adsorber might remove it.

Or we could just give them lots of space, clean water and plenty of good food.

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Puts hand up as other half of debate from facebook ;)

I've only been in this hobby for a relatively short time but as many of you are aware, I read, research and trawl a lot. From the very early days I've come across mention of something being present which may inhibit the growth of fry. There are definitely two camps of thought, those who believe and those who doubt - I dont think anyone can categorically dismiss the possibility.

In the end, it may not really matter to us as Betta hobbyists as what Raz states is very much the best practise of keeping and raising fry "give them lots of space, clean water and plenty of good food" - if this is done, then the belief that we are reducing the possiblity of any substance affecting the fry is true - whether that substance is growth inhibiting put there by the fry, or waste products, or uneaten food, or rising ammonia levels - water changes will take care of all of that. Lots of space gives us more stable water, and allows less stress for all fry due to less interaction with each other...and possibly dilutes any substance they excrete - and plenty of good food allows all the fry an opportunity to fill their bellies.

Poor nutrition can stunt growth and/or cause other malformations. Over crowding brings it's own set of problems. The same can be said for all species, although I acknowledge that some studies have shown some fish do excrete a substance which inhibits a siblings chances of survival. But in all species, with or without a substance inhibitor, nature provides a discrepency in offspring size. The more confident youngsters will always grow quicker because they get to the food first. In that struggle, they grow muscle tissue faster. They become bigger, stronger and faster because they eat more food, and because they eat more food, they become bigger stronger and faster. Nature also provides runts so predators have something other than the bigger offspring to sate their appetitie. In the wild, our small guys wouldnt last long and so all the remaining fish would be seen as of similar size...but there would always be an alpha, someone just a bit bigger than anyone else.

With my spawn (now I have figured out BBS), I make sure all my fry, particularly my little ones, have full orange bellies - and they all do by the end of feeding. My two smallest have even figured out they dont get harrassed if they eat the BBS hanging around the top of the water column, while the bigger boys cruise everywhere else. The bigger boys get the bigger share, but the little fellas are just as full and just as orange when everything has been eaten...but they are still the little fellas...

Sometimes nature deals out a flush to an individual in the height (length) genetics and they become the Robert Wadlow of their age, or spawn, as the case may be...

In the end, what I was trying to put across on FB as I will here, is there may be a GIS, or it may just be natural selection at work, but it needs to be explained to all hobbyists that either is a possibility, and neither is an explanation on it's own (until a number scientific processes prove the existence of a GIS), but regardless of any of that, good fish keeping practises need to be adhered to and if done so, then, at best, the question and hypothesis becomes an interesting side note, and your fry have the best chance of growing up happy and healthy (which is what we all want anyway).

Edited by Brenton
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I agree exactly with you regarding the good fish keeping practices but it would be nice to conclusively determine whether its natural selection and survival of the fittest (which it may be) or is it a chemical substance that affects the spawn differing levels dependant on their strength.

For all we know it could be a substance excreted by the fry that affect themselves based on how much feed they get.

Or it could be the bullying of the larger fry that causes the "runts" to grow slower because they exert more energy in stressing. That theory could coincide with equal growth rates up to 4-5 weeks old where the growing starts to go askew.

I guess in the end I just want to know what goes in my tank and possible ways to counteract it.

I will state that there are growth inhibiting aubstances but whether or not betta fry excrete it specifically is unknown.

Time to test I guess :)

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I have to second much of Brenton's post here, I am a bit of a believer in the old Growth inhibiting hormone, and I've harped on long enough about it in previous posts to try and be eloquent about my reasons...

But I also agree with Razzi, while it's a great discussion, nobody is going to say that the end result isn't the same: Lots of good quality food, excellent water quality and appropriate environments help fry grow faster. If it's environmental or hormone related - sort of dosen't mater in the end.

I've had a 80+ head spawn be stunted in excellent water conditions, however when I took 20 of them out and put them into a smaller tank that I found easier to water change, the growth rates went through the roof. When they were jarred in separate water, they also bloomed.
There are probably several factors into what makes a fish blossom when it's jarred, but one major factor will be the lack of other hormones (if indeed they exist) from the other fish.

The other consideration is their natural environments, imagine a successful spawn of 80 betta in the wild - potentially in a smaller body of water.
80 fry get tails, mum is probably around, so is dad.
Mum might eat 10, dad might defend his brood from her (potentially killing her) ...oh, this is getting morbid but stay with me...

let's say there are a few weak ones, so we're down to 60 by the first week - limited resources, natural factors... some will grow quicker than others

Could be genetic, could be from a growth inhibiting hormone... Let's not forget about the survival of the fittest - 60 fry are not going to be there at the end when they are ready to spawn again, let's face it.

I say 15 blossom, grow faster, and quickly double in size - the smaller ones become food, and the bigger fight until the first pair decide to find a quiet corner and spawn.

All a bit quick in the explanation, but in nature, there's going to be faster growers, more naturally aggressive with food - and the runts are gunna get eaten.
I have the Lion' King song "the circle of life" in my head now.

but there's 2 cents, spend it wisely.

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...I've had a 80+ head spawn be stunted in excellent water conditions, ...

When you say "excellent water conditions" are you saying you were monitoring ammonia, nitrite and nitrate levels? Or were you just doing water changes? I've had measurable ammonia in fry tanks immediately after doing an 80% water change. Indeed there was still a little bit of ammonia present after doing a further 50% water change. That's when you know for sure that the tank is too small for the number of fry, or that you're not doing sufficient water changes, or that the filter is doing diddly squat. Doesn't prove the presence of a hormone though. Not saying the hormone isn't part of the picture, just saying you haven't isolated that as the only contributing factor to the growth rate.

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Yeah, totally - but my whole argument is that while I'm not a scientist, I have only a few tools at my disposal (that I test monthly) and I can't tell if hormones are or are not a factor... it's still inconclusive, this would be a good myth to bust.
I have my opinion in what I think is going on, but I can't say fo' sho.

It could have even been environmental elements that helped the 20 blossom, I had heaps more cover in plants and a whole different tank - so who knows?

(I do full tests in my stable display tanks and twice weekly water changes with a ph water test weekly and a full Nitrite, Nitrate, GH, Ammonia done monthly)
I like the pretty colours.

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Ooooh pretty colours!!!

Thanks ness, now you got me sidetracked!! :mellow:

Anyways, all the input from everyone is awesome. Plenty to think about. Obviously good fry care is fundamental to good growth, but it'd be nice to justify why we go to the extra effort for these tiny babies.

I'd love to do some experiments in the future to test possible existence of the mysterious substances that may or may not be affecting the wonderful species of bettas.

Especially considering that if we look at wilds we do nowhere near the same amount of work and get fairly respectable growth rates. Guess it will remain a mystery for us all :(

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