The Magic Water Theory

Dear Professor

As you may already know, most of my posts are related to breeding. I have been doing some research about Discus since I want to breed them in the future. One of the things I came across was a YouTube video showcasing an Old Discus Hatchery.This hatchery birthed the first solid blue strain of Discus.

In the video the guy speaks about an old water circulation system that is in use on one end of the hatchery. Basically water flows from all the tanks into a pump and are delivered back to each tank through one common pipe system.

His theory is that when a female spawns, she releases pheromones and these circulate to all the tanks and trigger other females to also spawn. Is this theory true? Could this theory apply to Angelfish as well?

I await your exceptional response

Kind Regards

TM

 

Hi TM,

Yes, this theory was popular in days gone by, but there has never been any scientific evidence to prove this. In my opinion this is also not very likely, as I know of no evidence of pheromones in fishes in any case.

Completely opposite to this, I think that the consensus of opinion is that the addition of fresh water to a tank containing discus will stimulate them to spawn. The drop in temperature and the rising pH as a result of the water change is known to stimulate spawning.

What I would also like to mention to you is that with hybrid discus, you never have a problem to induce them to spawn. I actually prefer it if they do not spawn all the time as they can exhaust themselves. I also do not want them to spawn when they are too small as the spawning will stunt their growth. When I find that a too young pair spawns, I actually purposely separate them to stop this.

The reason why in the old discus hatchery there was this emphasis on inducing fishes to spawn was because wild caught fishes are difficult to induce to spawn. I have first hand experience of this now as I am trying to get my wild caught Curipera discus to spawn and they are difficult to get so far. However, I use water changes and that is still the best as far as modern discus keepers can agree on.

Kind regards,

Dirk

 

Hi Professor


Just to keep on the Discus side of things. . .

When Discus start free swimming, the more doninant release a growth stunt hormone into the water. I just want to know, Doesn't the Dominant Discus, in effect, stunt itself since the hormone is being released in the same water as the Fish's siblings?

I own a stunted baby Discus but he/she seems to be growing again. Do they stop releasing the hormone at a certain age?

Regards

TM

EDIT: Before anyone suggests I do water changes . . .I do this regularly to prevent my fish getting stunted.

 

Hi TM,

Again this story about the stunting hormone being released into the water is unproven although a lot has been speculated about it. I do not believe it because my fishes are all together in a recirculating setup, yet in a group of fishes that are together in one tank the biggest still grows faster, although in other tanks which are contact with this larger fishes are also growing and this should stunt the ones in other tanks if this theory was correct. However, growth is not stunted and this can only be ascribed to physical presence and physical dominance in one tank where they are all living together. Big discus quickly manage to psyche smaller ones ones out to the point where they will not dare to eat and if discus are not fed properly for 4 to 5 days they are in trouble and will start believing that they should die and the bigger chaps may let them believe that regularly by head butting them again and again. There are three ways of overcoming this: Strong feeding so that the smaller ones always get enough food, keeping a large enough group of fishes, and moving big dominant fishes into a group of even larger ones to stop their dominance. I do the last of these as I keep enough discus.

However, from my biochemistry background as well, I cannot see any scientific grounds for this stunting hormone theory.

And I would agree that water changes have nothing to do with this either.

Kind regards,

Dirk