The rice farmers in the Kathmandu valley plant their rice very close together, and most of the rice fields are only flooded at intervals to maintain the necessary amount of water.
Experiments on fish culture in rice fields were carried out by Major Gurung, a progressive farmer, who planted a well tillering Japanese rice variety at the prescribed spacing recommended by the Department of Agriculture. The bunds around the rice fields were increased from 0.3 to 1 m in height. Trenches 1 m wide and 0.3 m deep along the edge of the bund gave the fish an opportunity to return to deeper water when and if the level of the impounded water began to lower; for example, because of a broken water lead, a heavy flood washing away bund or water lead, etc. For about 40 days the maximum water level was maintained at 40 to 50 cm.
On Major Gurung's farm the initial experiment was started before the expert arrived without any alteration to the rice field. The results of operations in 1964 were promising as indicated below.
| Expenditure | NRs 1 | |
| Cost of fish fry and fingerlings | 26 – 50 | |
| Collection of fish | 6 | |
| Reinforcement of bunds | 150 | |
| Production | ||
Fish - 70 kg (150 lb) common carp ranging from 50 to 500 g per 1 000 m2 | 420 | |
Rice - The rice grown on the plots with fish was better than that on the others. On each ropani (500 m2) 16 pathi more rice was produced than in previous years. Additional net profit for the year: | ||
| Rice | 192 | |
| Fish | 247.50 | |
| The experiment was repeated by the Department of Fisheries on a plot of 8 ropani (4 000 m2): | ||
| Expenditure | ||
| Inlets and outlets, cemented in situ | 180 | |
| 2 000 carp fry (total weight 2 400 g) | 100 | |
| Production | ||
Total yield of 183 kg (405 lb) after 100 growing days in water above 11°C | 1 375 | |
| Value of Rice | 1 675 | |
1 U.S.$1.00 = NRs 10.12 in 1969
The yield of rice was not over the average as reported by Major Gurung. The lower yield was probably due to the removal of the topsoil of most of the rice field to make bricks, and the usual quantity of fertilizer was not used on the rice.
Major Gurung's neighbours started copying his efforts. On the expert's last visit to the site in March 1968 he noted that Major Gurung and others were seeking land and owners who would lease land for the combination of rice-cum-fish culture. In the event that out of 16 000 ha of rice fields in Kathmandu some 400 ha should be suitable for rice-cum-fish culture, the problem of supplying fish for the dense and growing population would be solved. The expert was convinced that more than 400 ha could be used to grow fish as well as rice, followed by the usual crops of wheat, beans and potatoes.
Rice-cum-fish culture in the Terai will be much simpler because bunds 0.6 – 1 m high already exist as a protection against floods from heavy rains. In order to achieve success, it should only be necessary to build additional structures, (i.e. fish canals, inlets and outlets;) and to accept the advice of the Department of Agriculture to plant a tillering variety of rice and sow it according to their instructions. It will be possible to carry out a large scale experiment on ricefield fish culture at Tejpur Belachapi on completion of the fish farm there.
