How many parameters did you take? Which parameter fluctuated most? Whether weekly/monthly fluctuation of the fluctuated parameter is significant. If not then it is not due to the parameter but if yes then you can think about it. In my opinion there will be fluctuation but not such that it can greatly affect length, weight and FCR.

Dear Rakesh,

Thanks for your answer. The water parameters are: pH, salinity, NO2-N, TAN, alkalinity, COD Mn (TOM) and phytoplankton abundance by class.

I found that each parameter tend to raise (e.g. NO2-N, TAN) and not fluctuated. But the raising slope different for each pond. I am about thinking to calculate each of the parameter difference between consecutive week and stated as d. Then re-correlate the production parameters and this d's (d-pH, d-NO2-N, d-TAN, etc) every week. Does it make any sense to you?

Not my expertise, shrimp culture. Are there water level, influx of stormwater, temperature differences? Water level change can be done with transducer adjusted if needed for barometric pressure, water temperature is fairly easy to measure at some representative depth. Is food source stable, do issues with blue green or other algae accumulate? You may also want to collect data on rainfall, tidal interactions if involved, salinity/freshwater interface depth if present and changing. I do not know if dissolved oxygen could be a factor. Perhaps even solar radiation during sunny and cloudy periods could be considered.

Kindly see this..

http://ageconsearch.umn.edu/bitstream/211233/2/22.%20JBAU-%20722-15%20.pdf

Explore here also...

http://www.fao.org/docrep/field/003/ac210e/AC210E09.htm

More to see here...

http://temp.biomin.net/hr/istrazivacki-centar/clanci/articles-details/article/monitoring-pond-water-quality-to-improve-shrimp-and-fish-production/

Surf this too..

http://shrimpfarminghowto.com/shrimp-farm-water-quality-management/

More to explore...

https://www.extension.purdue.edu/extmedia/as/as-503.html

Should also be seen..

http://www.vietlinhjsc.com/en/aquaculture/shrimp-farming-in-areas-affected-by-diseases-2015-10-pond-management.asp

This may help also...

https://www.maheshaqua.com/info-center/water-quality-management/

Also see here..

http://www.transinstruments.com/aquaculture/