Twelve years of fish-duck co-farming — and the management tricks to show for it
Chen Chao has farmed grass carp for 12 years on a 28-mu pond in Yuwotou Town, raising mainly "tongwei" grass carp. For 12 years he has combined fish-duck co-farming with some bottom fish in the mix. In his view the model improves water circulation, and the duck droppings serve as feed for the bottom fish — both fish and ducks grow well and farm income rises. Today his pond produces about 130,000 jin (65 t) of ducks a year, plus 1,300–1,400 jin/mu of mixed bottom fish as a bonus.
For the grass carp, Chen uses rotational catch-and-restock with no full pond drainage: he catches and restocks any time, keeping the grass carp density at roughly 1,300–1,700 per mu all year — large fish around 2.5–3 jin, medium 1–1.5 jin, small around 0.5 jin. This keeps pond space from filling up, raises feed conversion, and produces more uniform grass carp with better marketability — especially at the late stage when big fish fetch good prices.
To make the most of this model, Chen sources quality fry from Zhongshan Huangpu and makes sure they are vaccinated twice to improve survival. The pond level is relatively shallow, so he conditions the bottom regularly and uses internal products to keep the grass carp's liver and gut healthy. Twelve years of refining have made his technique mature — he is now planning to expand.
A distinctive aeration setup: aggressive feeding, fast growth
Fish-duck co-farming is common in Yuwotou, but few farmers exploit it as well as Chen. His secret is a clever aeration arrangement: on the 28-mu pond he runs 9 paddle-type aerators, 1 water-wheel aerator (the "rake machine") and 1 bottom aeration unit. Electricity runs to about 3,000 yuan per month, but Chen believes you have to spend to earn.
The water-wheel "rake machine" — normally seen on shrimp ponds — is his unusual touch on a grass-carp pond. He adopted it after testing and finding it genuinely effective: it makes aeration more flexible, greatly strengthens water circulation (easing the eutrophication pressure from fish-duck farming), and speeds up water exchange between layers — on hot days it drops the surface water temperature by about 3 °C.
For bottom aeration he does something special too: starting from the feed blower, he extends bottom aeration over two mu, using a Roots blower feeding nano microporous tubing on the pond bottom — richer dissolved oxygen at the bottom, fewer harmful substances, and no more fish gasping at the surface. Running several aerators takes careful management: the water-wheel runs from 8:00 to 17:00, and the aerators run at night.
Because dissolved oxygen is so well managed, when ponds around him were losing hundreds or thousands of jin of fish to disease in the first half of the year, his pond was unaffected — and on overcast, rainy days when most farmers cut feed for fear of low oxygen, Chen feeds normally. In peak season he feeds 18 bags a day, three more than the average farmer; over a year the 28-mu pond consumes more than 110 tonnes of feed.
With the feed going in, his grass carp grow fast and big: he can sell half the pond's stock in six months, taking advantage of good prices — at least two extra batches a year compared with other farmers.