Raanan´s response on fishponds
I would like first to congratulate Peggy having succeeded to get together so many efficient experts to an interesting brain storming concerning Microfarm.
An important conclusion is about the physical planning of every single Microfarm units. The fish pond should be installed in the higher topographical area in order to direct the outlet water by gravitation to the open field crops.
It is necessary to emphasize that in this Microfarm case in the Siera Negra, we are dealing with basic root initially subsistence farmers where the majority are poor single mothers as head of the family. This means that the technologies in the initial stage of the project as to be simple.
I assume that the introduction of drip irrigation and filters will be on a later stage.
I will recommend that one family unit out of the first 15 as planned, will be served as experimental and demonstrative. On this farm new proposed technologies could be tested. Also on this farm appropriate knowledge will be generated.
I would like to propose another simple technology called Wet-land to recycle the water coming out from the fish ponds. On this wetland area, grasses and legumes could be grown to be use as fodder for the animal husbandry.
This wetland could be use also for any other need of recycling drained water or home use water on the Microfarm.
I am suggesting again to reconsider having more than tilapia fish in the ponds. Various species of fish can take advantage of different levels of the pond. Catfish are living on the bottom, carps in the middle and tilapia on the surface. This will result a higher efficiency of fish production in the ponds. An ecological balance will be reached and the water will have less algae and sediments and much more clean. I will appreciate the opinion of Dr. Alberto Guzman from University of Guadalajara , on this point.
From the point of view of having enough oxygen concentration in the fish ponds water, it is recommend to construct shallow fish ponds. Oxygen generating devices could be use but electric energy must be on the spot, which I think is not real on this stage.
All the best,