Table 3 presents the data on the growth of broodfish during preparation and the comparision of the weight increase of each species in traditionally managed pond and in pond treated with improved technology.
TABLE 3
GROWTH OF BROODFISH IN OFF SEASON PERIOD
| Species | Management method | Average weight of broodfish (kg) | Weight increase | Relative Difference | ||||
| 25-Oct-90 | 27-Nov-90 | 31-Jan-91 | 20-Feb-91 | 16-Mar-91 | ||||
| Mrigal | Traditional* | 1.4 | 1.8 | 2.1 | 2.4 | 2.5 | 79% | 53% |
| Improved** | 1.4 | 2.2 | 2.3 | 2.9 | 3.1 | 121% | ||
| Rohu | Traditional | 1.3 | 2.0 | 2.2 | 2.2 | 2.4 | 85% | 18% |
| Improved | 1.6 | 2.2 | 2.5 | 2.9 | 3.2 | 100% | ||
| Grass carp | Traditional | 1.8 | 2.1 | 2.5 | 2.6 | 2.7 | 50% | 62% |
| Improved | 2.1 | 2.6 | 3.5 | 3.7 | 3.8 | 81% | ||
| Catla | Traditional | 5.5 | 6.8 | 7.0 | 7.1 | 7.2 | 31% | 22% |
| Improved | 5.8 | 7.1 | 7.2 | 7.9 | 8.0 | 38% | ||
As it was revealed growth of fish was far better in pond managed with improved technology than in traditionally treated pond. Supposing that the gonad development is better in those fish which have better growth rate, the adventage of improved technology is clear. As the relative differences in the weight increase between the two management methods are the biggest at grass carp and mrigal (62% and 53 % respectively), we can state that the technology in use is the best for these two species. Though the other two reared species had also better growth in pond managed with improved technology, the relative differences between traditionally managed pond and the pond treated with improved technology are less, only 18 % in rohu and 22 % in catla.
Breeding time and production of broodfish with improved technology in pond no. 3 are shown in Table 4. The broodfish in this pond reached full maturity 2–3 weeks earlier than the first matured fish occured in traditionally managed ponds. Average fry production of broodfish originated from pond no. 3 was 50,000 feeding fry from 1 kg female. Those fully matured females wich were taken for breeding from traditionally managed broodfish ponds produced only 40,000 feeding fry per kg body weight, which is 20% less than in pond managed with improved technology.
TABLE 4
PRODUCTIVITY OF BROODFISH IN POND NO.3
| Species | Breeding time | No. of injected female Pc | Average weight Kg | Ovulation | No. of dry eggs Million | Fertilization % | Hatchlin g % | No. of fry Million | ||
| Complete Pc | Partial Pc | No Pc | ||||||||
| Mirror carp | February | 10 | 2.5 | 7 | 1 | 2 | 2.5 | 80 | 95 | 1.9 |
| March | 5 | 3.2 | 4 | - | 1 | 1.5 | 75 | 90 | 1.0 | |
| Mrigal | March | 16 | 2.0 | 11 | - | 5 | 2.0 | 60 | 90 | 1.1 |
| April | 21 | 2.4 | 18 | 1 | 2 | 3.5 | 75 | 95 | 2.5 | |
| May | 18 | 2.2 | 16 | - | 2 | 3.6 | 80 | 95 | 2.7 | |
| Rohu | April | 17 | 2.4 | 13 | 1 | 3 | 2.5 | 60 | 90 | 1.4 |
| May | 12 | 2.1 | 10 | - | 2 | 2.0 | 75 | 95 | 1.4 | |
| Grass carp | April | 3.0 | 5.3 | 3 | - | - | 1.2 | 75 | 95 | 0.9 |
| May | 2 | 5.5 | 2 | - | - | 1.0 | 85 | 98 | 0.8 | |
| Shorput i | April | 11 | 0.9 | 8 | 1 | 2 | 3.5 | 60 | 90 | 1.9 |
| May | 5 | 1.0 | 4 | - | 1 | 1.5 | 75 | 95 | 1.1 | |
| Silver Carp | March | 15 | 3.0 | 15 | - | - | 3.6 | 85 | 98 | 3.0 |
| Catla | April | 2 | 8.5 | - | 2 | - | 0.5 | 30 | 5 | 0.1 |
| May | 6 | 8.3 | - | - | 6 | - | - | - | - | |
It is difficult to conclude, wheather the improved feed applied, or the frequent manuring had primarily positive effect on broodfish quality. However, the fact that at the end of April, mass blooming of Cladocerans was detected in pond no. 3, which are the best source of animal protein for majority of broodfish, we suppose that the most important feature of the improved technology is the frequent small dose manuring and daily feeding of green material (duckweed), instead of feeding fish with artificial feed containing high percentage of animal protein.
About 50 percent of earlier stripped females reached the maturity after 1 month preparation and gave sufficient quantity of good quality eggs (Table 5).
TABLE 5
PRODUCTIVITY OF BROODFISH AT REPEATED BREEDING
| Species | Ratio (%) | Egg production (% of body weight) |
| Mrigal | 33 | 10 |
| Rohu | 66 | 15 |
| Grass carp | 50 | 13 |
| Catla* | - | - |
* Catla was not sexually riped
Results of repeated breeding of grass carps are detailed in Table 6. As data indicated only those fish produced acceptable quality eggs, which were qualified as “excellent” by visual examination at broodfish selection. Those wich were qualified as “acceptable” (i.e. belly was only slightly swollen) gave bad quality eggs. However, fish havinng similar external feature in peak season would have been able to produce good quality eggs. Contrary to grass carp, rohu and mrigal, having only “acceptable belly” gave good quality eggs. The latency time before ovulation in excellent fish is shorter than in acceptable fish.
TABLE 6
RESULTS OF REPEATED BREEDING OF GRASS CRP
| Weight of female kg | Egg production g | Latency time hours | Rate of fertilization % | Broodfish quality by visual examination |
| 2.9 | 480 | 5.0 | 98 | Excellent |
| 3.3 | 380 | 5.0 | 98 | Excellent |
| 2.8 | 470 | 7.0 | 70 | Excellent |
| 2.9 | 410 | 7.0 | 70 | Excellent |
| 4.0 | 580 | 6.5 | 70 | Excellent |
| 3.3 | 280 | 8.5 | 30 | Acceptable |
| 2.8 | 220 | 9.0 | 30* | Acceptable |
* The egg were not swollen properly and all the embrios died
Catla broodfish reared in Natore FSMF were too young to reproduce. It is the explanation of that the females not matured during preparation for second breeding.
Catla broodfish of pond no. 3 (in Rajshahi) were not succesfully bred untill middle of May. The delay in final maturation may be due to the cummulative effect of high water hardness prevailing in this farm and the unusual hot period during spring of 1992.
