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Water change and agression - Linked?
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Ciklido
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Joined: 06 Aug 2005
Location: Ontario, Canada

PostPosted: 2008.09.26(Fri)14:18    Post subject: Water change and agression - Linked? Reply with quote

Abstract: http://tinyurl.com/3lqdbv

Of what I recall I have always observed in my african cichlids that whenever I did a water change the aggression of the fish became unstable and the dominant fish would have to be unusually aggressive so that the order of hierarchy would remain as previous. This was just a thought, however. this study in Brazil in the University of Sao Paolo & University of Estadual Paulista, experimentally researched the correlation between (1) water renewal (water change), and (2) aggression in Nile Tilapia. Does this apply to your fish?


The reason behind this seemingly true correlation interestingly enough, lies behind a chemical communication system within the aquarium.



<Corrected Lenght for display -- Irons>
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T48-4PG8H1B-2&_user=10&_rdoc=1&_fmt=
&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=10
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number6
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Location: Ontario, Canada

PostPosted: 2008.09.26(Fri)19:43    Post subject: Reply with quote

chemical communication? or I know you by smell and sight?

In systems with a constant flux of new water, you effectively remove 1/2 the ability of the fish to know each other.

This is not the same thing as a water change. I would suggest it would be incorrect to take the results of this test and think it applies to a totally different situation.

Mbuna do not get more aggressive after a water change. I would suggest you are mistaking friskiness for agression. After a large water change, many cichlids breeding behavior is triggered. Desire to spawn might be mistaken for aggression... territory is a very important part of mbuna mating strategies.
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UncleWillie
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Joined: 26 Nov 2007
Location: Georgia, USA

PostPosted: 2008.09.27(Sat)9:40    Post subject: Reply with quote

Certainly interesting. I would have to agree that water-change is not the same thing as water-renewal. I think that there is nothing 'constant' about many water changes. A constant input of 'new' water and output of 'old' water - a flow if you will - would more reasonably fit this description.
I think number6 has a good point about friskiness - triggers caused by the 'new' water's chemistry, temperature, etc.
Though it is hard without access to the entire publication.
Chemical release is also hard to interpret. As number6 said, is it sight and sound? Or is it really a chemical release or some sort. I know many minnows, when attacked and wounded - release large amount of a chemical in the water that when smelled by other minnows of the same species - they flee the area.
Interesting stuff - just wish I could read the whole thing.
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Ciklido
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PostPosted: 2008.09.29(Mon)11:22    Post subject: Reply with quote

First of all I am not "applying it to a new situation" I am only trying to pin-point parts of this study to see if they actually do apply.

According to the article, it specifically references that Cichlids (no mention of execptions) are fish that do use "chemical cues". One ineteresting point stated is that Convict cihlids recognize their mates through chemical cues at night.

Now, when I said aggression, I merely implied a temporary increase in levels of agression (increase in frequncy of attacks).

The main reason I suggested this article is because the experimental fish were kept in 48L aquariums for 3 days, and then paired them in one (either renewed, or non-renewed tank) afterwhich they were recorded for three hours. Within the Renewed tanks, (40cm x 30cm x 40cm), they simply ran a tube acting as a drain on the bottom of the aquarium and added water through the top with a continous supply of new water. In the non-renewed it was just an aquarium with a controlled amount of water flow.

Anyhow, the study indicates that the chemical cues for dominance were only delivered by the dominant individual. So if rank signalizing is impaired, the dominant fish must once again "set" the heirarchy system and shortly after the chemical concentrations of the dominant fish would be stable. I was thinking that as long as the rank signalizing was impaired (by removal of old water and addition of new "fresh" water) and the concentration of the chemical cues were decreased, the dominant fish would hence attack more often for a limited period of time. The dominant fish as well as the subdominate fish would detect a decrease in the status-specific chemical.
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number6
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PostPosted: 2008.09.29(Mon)19:45    Post subject: Reply with quote

Ciklido wrote:
First of all I am not "applying it to a new situation" I am only trying to pin-point parts of this study to see if they actually do apply.


You are trying to apply behavior noted in tanks with complete refresh to tanks with partial water changes. You are trying to take situation A. and replace it with situation B. without due diligence.

You ARE applying it to a new situation.

If you would like to try and explain how a tank with partial water changes could be comparable to a tank with constant water flow, I'm all ears... I'm open to explanation, not denial.
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Ciklido
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PostPosted: 2008.09.30(Tue)13:23    Post subject: Reply with quote

So I guess my question is, if you did a 50 percent water change, by what factor would the chemical cues (concentration in chemical signals) decrease? And is it at all significant? Assuming that originally the chemical conc. was 100 percent.
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number6
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PostPosted: 2008.09.30(Tue)13:53    Post subject: Reply with quote

Now that is an excellent question.

If you could find studies that measured how many ppm of chemical solids were given off over "time box A." and a reference of how many ppm other fish reacted to, became stressed by, became very stressed by- then you might be able to hypothesize an answer to your original question... can a water change increase aggression?
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