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Anybody contemplating fish farming should learn all you can re the particular fishes biology and habits learn these and you are half way home.
Before you start digging a bloody big hole in the ground,check that the sub soil is capable of holding water and that you have a reliable water supply.
My figures are for the standard size I now build,this being 1 rai(1600sq met.)and able to carry a max water depth of 120cm in the centre out to 50cm at the edges with a slight slope to one end to aid final pumping and harvesting.
Slopes of the banks should be 5 to 1 ratio to help reduce erosion.
A pond such as this can usually be excavated by a big ford tractor and blade much cheaper and neater than an excavator,a tractor can operate up a 5 to 1 slope and spread its own fill.
If you are building adjacent ponds,make sure the margins are at least 5 metres wide as they erode to a degree in time and it is virtually impossible to renew the bund walls without building retaining walls.A wider area dividing the ponds can more easily be grassed and landscaped with fruit trees etc.
After filling the pond the first time ,the water will probably be muddy with suspended clay etc, dont just toss in your fry or fingerlings as soon as you have water,make sure the environment is ready to receive the fish.
I do this by priming the 1 rai pond initially with 12kg of triple super phosphate 0-45-0 and 6kg of Nitrogen 45-0-0
or alternatively 20 kg of 16-20-0 ,the triple super and urea is the most economical way as this is about 1000baht per 50kg bag giving 45%phosphate wheras Rabbit 16-20-0 at 680 baht a bag only provides 20% phosphate.
After about 10 days the water should start to clear and an algael bloom should become evidenton the surface, if it doesnt just give the pond a booster of 50%of the initial dose.
Dont worry if your pond becomes covered in green gunk ,it will die back and your water will turn a shade of green,Pla Nin love algae and it contains up to 50% protein.
What your are trying to achieve is green water where if you dip your arm in 2/3 rd of the way to your elbow and cock your wrist at right angles ,you should just be able to see the palm of your hand,this indicates a healthy population of micro-organisms and micro plankton which is Pla Nins primary natural food and very high in protein.
As phosphate levels drop, the water will become clearer ,indicating a booster shot of phosphate is required, to this end we add 5kg of 0-45-0 once a month.
My particular method of adding and distributing the fertiliser is to weigh out the dose int a 2foot x1.5 foot bag made from the fine blue netting commonly used here and hang it on a pole driven into the pond .I just direct the outlet stream from a 3 inch honda powered centrifigal pump at the bag and it dissolves slowly and spreads around the pond.
Pla Nin grown by this method do not need supplementary food to grow ,but we feed about 1.5 kg of fairly small 20% protein pellets per 1000 fish twice a day,this regiments the fish to come to you for food (handy when harvesting starts) and allows you to keep an eye on your fishes health and condition.
You can certainly grow your fish quicker than we do by feasting them up on copious amounts of high protein pellets ,but the profitability becomes marginal.
Our set up is geared to provide about 5000-6000kg via door sales and make fish available throughout the year. We are the only fish farm in an area of about 20 villages and this returns T/W about 1000 baht a day. (not me ,I,m only the unpaid fish hand)
Before jumping in and starting to dig that big hole in the ground ,always do a bit of market research,a heap of fish without a buyer is about as handy as a hole in the head.
If you keep your stocking rates to about 1000 fish/rai not many problems arise like dissolved oxy levels and disease
but for a 1 or 2 pond farm a 3inch honda centrifigal pump can be set up for aerating as well as pumping in and out.
We actually stock at double my recommended levels ,but I have fitted auto aeration to the ponds, this is better done retro ,after you learn more .
I got away with overstocking our first year and learnt a hard lesson when I tried it again,a big hole in the ground filled with 2 tonne of dead fish is a lesson I dont want any of you budding fish farmers to replicate.
