Fish
We use the Royal Carp as our main stock and can give good, sound advice on numbers per cubic metre that can be sustained naturally without any feed input. From birth to edible size you are looking at two years.
If it is not an intensive system, you will get no disease. Forget what you read in books about not letting water from one tank pollute the next for fear of spreading disease. Remember a river. Do the fish downstream die because there are fish upstream? No; because the natural system is balanced. We design for this.
Water: our most vital resource. We must store it when in abundance for use in periods of drought.
Whatever it is stored in - ponds lined with clay, old plastic tubs linked together, concrete tanks, lined natural depressions, etc., it has one major problem: mosquitos. Leave an area of still water for two weeks and you have tens of thousands of horrible, blood-sucking insects. Introduce fish and you have none. Breed a species of fish that you can eat and you have another resource. Pick the right balance of plant life and you have healthy fish in a self sustaining healthy environment. Plus, of course, you still have the water. Each of the 3, fifty ton irrigation tanks have been seeded with 20, one year old edible carp. One tank seeded per year. Each tank is connected, via stepped sections, so one tank feeds the other. Not, we are told, the correct way to breed fish, but of course in nature the top of the river feeds the lower reaches The fish are not fed but we have made sure there are enough pond plants to encourage the life they feed on. Again, after 4 years, we have no noted instances of disease and not one fish had died. The bottom tank of the three, and the first one we seeded, now has fish of about 1ft long and last year they bred for the first time. As far as we can tell, about 200 offspring survived the first year. We expect the original group to breed again this year and will be keeping notes on the maximum number of fish nature will allow each tank to hold.
Birds
As our trees have matured, we have also noted an increase in small bird population. At first these were considered as a pest as they were always eating the fruit. But, as the land returns to its natural balances, so they have returned to their natural food. Insects and bugs. Not only do they carry out this control function, but we have also noted the times they leave their droppings on the land. Its the same thing, as the water trickles. A little at a time but constant. We now calculate that several hundredweight of guano is deposited on our land every year by birds.