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1.
The compatibility and growth performance of silver barb Puntius gonionotus (Barbonymous gonionotus) with the three Indian major carps, i.e., Catla catla, Labeo rohita and Cirrhinus mrigala, were assessed in a 10‐month carp polyculture trial. Treatments T‐1, T‐2, T‐3 and T‐4 were stocked with three of the above four carp species, with an absence of silver barb, mrigal, rohu and catla, respectively, while all four species were stocked in treatment T‐5. The treatments were stocked at 6000 fingerlings ha−1, with an equal species ratio maintained in each treatment. Incorporation of silver barb into the polyculture system neither affected the survival of any carp irrespective of species combination nor yielded significant changes in biomass production among treatments, except for the one without catla, where it was significantly low. The study revealed a higher extent of competition between silver barb and rohu, perceptible from the lower growth of one in the presence of the other. Although a certain level of competition of silver barb with mrigal was evident, competition with catla was not perceptible. Irrespective of species combination with silver barb as a component species, similar total biomass production in treatments revealed the feasibility of its incorporation into the Indian major carp‐based polyculture practice without affecting the total yield.  相似文献   

2.
The compatibility of olive barb, Puntius sarana (Hamilton) with major carps was studied in grow-out carp polyculture system for one year in a set of nine earthen ponds of 0.08 ha each. Three different species combinations evaluated were Control: catla (Catla catla Ham.), silver carp (Hypophthalmichthys molitrix Valenciennes), rohu (Labeo rohita Hamilton) and mrigal (Cirrhinus mrigala Hamilton) at 0.5:0.5:1:1; T1: catla, silver carp, rohu and olive barb at 0.5:0.5:1:1 and T2: catla, silver carp, mrigal and olive barb at 0.5:0.5:1:1 at combined density of 7500 fingerlings/ha. While survival levels of the carps did not differ significantly in treatments (P > 0.05), silver carp recorded highest survival levels (94–96%) followed by olive barb (87–90%), mrigal (72–74%), rohu (72–73%) and catla (67–69%). The specific growth rate (SGR) and average harvested body weight (ABW) of catla and silver carp did not differ significantly among the treatments revealing their competition with mrigal or olive barb to be minimum. In absence of rohu in T2, both mrigal and olive barb showed higher SGR and ABW revealing minimal competition between these two species, while their lower performance in presence of rohu in Control and T1 indicated inter-specific competition with the latter. Such olive barb–rohu inter-specific competition, however, failed to yield significant effect on growth of rohu as revealed from its non-significant SGR difference in presence and absence of olive barb. The lower FCR (2.54 ± 0.06) and higher treatment biomass production (3418.4 ± 95.0 kg ha− 1 year− 1) in T1 with rohu–olive barb combination compared to T2 with mrigal–olive barb (2.84 ± 0.11; 3155.1 ± 104.7 kg ha− 1 year− 1) indicated feasibility and advantage of culturing rohu with olive barb rather than mrigal in carp polyculture. Further, similar biomass production in Control and T1 also indicated feasibility of replacing mrigal with olive barb in the grow-out carp polyculture system.  相似文献   

3.
The effects of fingerlings immersion in low‐dose benzocaine (15 and 30 mg L−1, silver carp and rohu) and quinaldine (100 μL L−1 silver crap and 250 μL L−1 rohu) for 1, 3 and 6 h on stress responses and survival of rohu, Labeo rohita and silver carp, Hypophthalmichthys molitrix fingerlings were evaluated in a transport simulation experiment. Both quinaldine and benzocaine showed low mortalities (0–2%). The total mortality in control (with no anaesthesia) was 30% for rohu and 14% for silver carp. Quinaldine and benzocaine‐treated fingerlings had significantly higher plasma chloride levels than the control in both species. Benzocaine, quinaldine, as well as the control, had an initial elevation of plasma cortisol levels. Benzocaine lost its effectiveness after 3 h exposure while quinaldine persisted throughout the 6 h experimental period. Both sedatives reduced bacterial build‐up compared with the control. No post‐exposure mortality was observed for any of the transport methods assessed 48 h after the treatment. This study suggests that the use of low‐dose benzocaine or quinaldine during transport has positive effect on the survival and health of rohu and silver carp fingerlings.  相似文献   

4.
A year‐long grow‐out carp polyculture trial was conducted in nine earthen ponds to study the growth performance of Kuria labeo (Labeo gonius) with the different major carps such as catla (Catla catla), silver carp (Hypophthalmichthys molitrix), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala). Suitable water quality parameters were maintained in ponds through intermittent liming, manuring and fertilization. Three different species combinations of carps were evaluated using silver carp and catla as the common species and varying other carp components as rohu–Kuria labeo, mrigal–Kuria labeo and rohu–mrigal in the three treatments. The ponds were stocked at a combined density of 7500 fingerlings ha?1. Silver carp and catla showed similar growth performances in all the three combinations, suggesting that other carps in the combination do not have any differential influence on their growth. Kuria labeo was compatible with rohu, while competition was observed with mrigal. Although growth performance of Kuria labeo was inferior to that of mrigal, better compatibility of Kuria labeo with rohu helped this combination to yield a biomass equivalent to the mrigal–rohu combination, suggesting feasibility to use Kuria labeo as an alternative species to mrigal in the major carp polyculture system without compromising the total biomass yield.  相似文献   

5.
A study was conducted to optimize stocking density of freshwater prawn, Macrobrachium rosenbergii, in carp polyculture for 3 months in 10 experimental ponds of 80 m2. Five stocking densities of prawn, 2500, 5000, 7500, 10 000 and 12 500 ha?1, were assigned to treatments T1, T2, T3, T4 and T5 respectively. The densities of catla, Catla catla, rohu, Labeo rohita and silver carp, Hypophthalmicthys molitrix, were 2500, 5000, and 2500 ha?1, respectively, in each treatment. Each treatment had two replicate ponds. The mean initial weights of prawn, catla, rohu and silver carp were 1.1±0.02, 8.28±0.1, 25.2±1.1 and 36.32±1.2 g respectively. A pelleted diet containing 30% protein was prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses, and was fed twice daily at a rate of 5% of fish biomass. Water quality parameters were measured fortnightly and the ranges of temperature, pH and dissolved oxygen were 27.5–1.3°C, 6.9–8.6 and 4.5–8.6 mg L?1 respectively. Feed conversion ratios ranged from 2.05 to 2.20 among the treatments. Per cent survival (%) of prawns ranged from 72% to 78%, while it varied from 80% to 93%, 90% to 95% and 90% to 92% for catla, rohu and silver carp respectively. The results showed that there were no significant differences among the weight gains of prawn and carp in different treatments. However, the overall total production of prawn and fish together was significantly (P<0.05) higher in T3 and T4 compared with other treatments. The total production for 3 months ranged between 2618 and 2916 kg ha?1. The production of prawn was significantly higher (361.3 kg ha?1) in T5 with a highest stocking density of 12 500 prawn ha?1. Although there was no significant difference (P>0.05) between the total production of prawn and fish together in T3 and T4, the highest net profit (Tk. 69 006 ha?1) was obtained in T4. Therefore, from the result of the study it may be concluded that a stocking ratio of 4:1:2:1 of prawn:catla:rohu:silver carp at a total density of 20 000 ha?1 may be recommended for prawn–carp polyculture in ponds.  相似文献   

6.
Growth performance of kuria labeo, Labeo gonius as a component species in the major carp polyculture system was evaluated at two incorporation levels against a control without the species through a year‐round grow‐out study in nine earthen ponds (0.08 ha). Three species ratio of catla, silver carp, rohu, mrigal and kuria labeo at 15:15:40:30:0 (T‐1: control), 15:15:40:20:10 (T‐2) and 15:15:40:10:20 (T‐3) were evaluated as three treatments. The carps were stocked at a combined density of 7500 fingerlings ha?1. Silver carp demonstrated the highest survival (75–81%) followed by rohu (70–76%), catla (69–76%), kuria labeo (69–71%) and mrigal (67–69%). Species‐wise yield attributes such as survival, harvest weight, SGR and biomass yield of silver carp, catla and rohu were similar in their respective treatments. Kuria labeo at 10% inclusion demonstrated 12% higher harvest weight than its 20% inclusion. However, such higher weight gain could not affect the total biomass yields of carps which remained similar among the treatments. Furthermore, harvest weight of kuria labeo at 10% inclusion was comparable to that of mrigal when the latter incorporated at 20–30% level. Therefore, the study suggested 10% to be a suitable incorporation level for kuria labeo in the commercial grow‐out carp polyculture system.  相似文献   

7.
Digestive enzymes of Cirrhinus mrigala (Ham.) were studied during ontogenic development. Specific amylase activity was detected in first feeding fish. The enzyme activity decreased up to day‐18 and then it increased with the age of fish to reach the highest level on day‐34. Protease activity was 28.61 ± 8.90 mU mg protein?1 min?1 on day‐4 and increased with the age throughout the study period. Trypsin activity was 31.86 ± 1.12 mU mg protein?1 min?1 on day‐4. The activity decreased up to day‐10 and from day‐12 onwards increased up to day‐26. Chymotrypsin activity was 14.56 ± 2.74 mU mg protein?1 min?1on day‐4 and constantly increased up to day‐26. A significant increase in lipase activity was observed between days‐24 and 34. SDS‐PAGE and substrate SDS‐PAGE showed the diversity of protein (17.4–127.8 kDa) and protease activity bands (16.6–88.8 kDa) during ontogenesis. Soybean trypsin inhibitor, phenyl methyl sulphonyl fluoride, N‐α‐p‐tosyl‐l ‐lysine chloromethylketone and N‐tosyl‐l ‐phenylalanine chloromethylketone inhibited the protease activity up to 79.72–97.21, 65.55–94.83, 45.41–75.31 and 40.78–64.72%, respectively. Inhibition study in substrate SDS‐PAGE revealed the abundance of serine proteases and the presence of isoforms of trypsin and chymotrypsin. Ethylenediamine‐tetraacetate showed 5.56–22.78% inhibition of metal ion‐specific enzyme activity.  相似文献   

8.
An experiment was conducted from December 2003 to April 2004 to observe the over‐wintering growth of freshwater prawn, Macrobrachium rosenbergii, with catla, Catla catla and rohu, Labeo rohita in polyculture using formulated diets. The study was conducted in eight experimental ponds, each 80 m2. Three experimental diets containing 30% protein were prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses (binder), and assigned to treatments T1, T2 and T3 respectively. A commercial diet from Saudi‐Bangla Fish Feed was assigned to T4 (reference diet). Each treatment had two replicate ponds. Juvenile prawns and catla and rohu fingerlings (initial weight 1.60±0.10, 30.0±1.2 and 25.0±1.1 g respectively) were stocked at a ratio of 2:1:1 (prawn:catla:rohu). A total of 160 prawn and fish (20 000 ha?1) were stocked in each pond. Fish were fed twice daily at 3% body weight (b.w.) for the first 3 months and 5% b.w. for the last 2 months. Prawns in T1 fed diet 1 had significantly higher (P<0.05) weight gain compared with that of T3. The reference group and T2 had intermediate values not significantly different from either. Weight gains of catla and rohu were significantly higher in T1. The feed conversion ratio values of different diets ranged between 1.89 and 2.13. Survival (%) ranged from 90.0% to 95.0% for catla, 87.5% to 92.5% for rohu and 70.0% to 76.3% for M. rosenbergii, and there were no significant differences (P>0.05) among different treatments. Total production ranged between 2196 and 2679 kg ha?1, with T1 showing significantly higher production and net profit (taka 56 531.9 ha?1). The results of the study demonstrated that it is possible to culture M. rosenbergii with carp in polyculture during the winter utilizing the late‐produced PLs. Further study is needed to determine the optimum stocking density of M. rosenbergii in carp polyculture.  相似文献   

9.
Previous research showed that stocking 1.5 rohu (Labeo rohita) and 0.5 common carp (Cyprinus carpio) m−2 yields the highest production in small holder ponds in Bangladesh. The present study looked into the effects of additional stocking of Nile tilapia (Oreochromis nilotica) in fed or non‐fed ponds on water quality and fish production. A low, additional stocking density of 0.2 Nile tilapia m−2 was tested. All treatments were executed in triplicate in 100 m2 ponds and the duration of the experiment was 4.5 months. The results showed that tilapia addition increased nutrient concentrations and reduced total suspended solid concentration and phytoplankton biomass (P<0.05). Tilapia stocking resulted in additional production without affecting the growth and production of rohu and common carp. Supplemental feeding increased the nitrogen and phosphorus concentrations, phytoplankton availability and the growth and production of rohu and common carp (P<0.01). The combination of supplemental feeding and tilapia stocking resulted in a higher net yield than the other treatments (P<0.05). Stocking 1.5 rohu, 0.5 common carp and 0.2 tilapia m−2 in fed‐ponds is a good culture combination for polyculture farmers in South Asia.  相似文献   

10.
This experiment was carried out in the framework of a project to develop a viable fish polyculture technology under Bangladeshi conditions that allows simultaneous fish production of small indigenous species for the farmers' family consumption and of large carp species as a cash crop. The objectives of this experiment were to assess the effects on fish performance and on the environment of adding 20% large fish to the basic ‘cash crop’ carp–small fish polyculture consisting of 10 000 fish ha?1 of the large carp rohu Labeo rohita (Hamilton), catla Catla catla (Hamilton) and common carp Cyprinus carpio (L.) at a species ratio 1:1:1, and 15 000 fish ha?1 of each small indigenous fish punti Puntius sophore (Hamilton) and mola Amblypharyngodon mola (Hamilton) (control). The treatment ponds were stocked with additional 2000 large fish ha?1, either all rohu, or all catla, or all common carp, or half rohu and half common carp, or half catla and half common carp. The results obtained and the analysis of interactions through the food web that affect food resource availability of the different fish species and account for the trends and differences observed among treatments confirm the positive effect of common carp on rohu reported in previous experiments and show that a 20% increase in large carps stocking neither affect the survival of the large carps nor reduce harvesting biomass of the small fish for the farmer's family consumption. Increased stocking densities of each large carp species did not significantly reduce its own harvesting weight and mean growth rate, while significantly increased rohu and catla (but not common carp) harvesting biomass and yield. The complex relations between species led to inter‐ and intraspecific competition, which in some treatments increased growth or yield of one species and in other treatments of other species, so that the gains on one species and the losses on the other led to no significant total harvested biomass differences between treatments. Yet, the results herein reported may help farmers to select their species stocking ratios. Thus, if the main target of the farmer is rohu, then a stocking density increase of 10% common carp and 10% rohu would improve rohu growth rate (due to common carp) and result in 50% higher rohu harvesting biomass and yield. If the main target of the farmer is catla, then a 20% increase in catla stocking density would lead to 20% higher catla harvesting biomass.  相似文献   

11.
The in vitro inhibitory effect of protease inhibitors from four seed extracts (soybean, grasspea, black gram and horse gram) on digestive proteases of rohu was assessed by enzyme inhibition assay and substrate sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. High proteolytic activity was detected in the intestinal extract of rohu (Labeo rohita) fingerlings at two different pH ranges (8–8.5 and 10–11). That protein digestion occurs mainly in the alkaline condition in this fish without a stomach is evident from very high trypsin activity (0.95±0.04 benzoyl‐dl ‐arginine‐p‐nitroanilide U mg protein−1) in the intestine. In case of grass pea seed, more than 50% inhibition of alkaline protease activity was recorded when the ratio of inhibitor to enzyme was 9.41 μg U−1. More than 40% inhibition of protease activity was recorded in case of horse gram seed when the ratio of inhibitor to enzyme was 5.51 μg U−1. Black gram at 11.0 μg U−1 and soybean seed proteins at 62.75 μg U−1 resulted in 50% and more than 30% inhibition of digestive protease activity in rohu fingerlings respectively. A plot of the inhibition values obtained by changing the relative concentrations of enzyme/inhibitor resulted in different dose–response curves for different protein sources. The use of substrate gel electrophoresis allowed the visualization of the aforementioned differences in inhibition. Each seed extract produced a characteristic profile of protease inhibition. It is concluded that protease inhibitors present in plant protein sources adversely affect the digestive proteases in fish and hence there is a need to eliminate/reduce the amount of such inhibitors through proper processing before incorporation into aquafeeds.  相似文献   

12.
An experiment was conducted to compare rice straw mat and kanchi (bamboo sticks) as substrates in periphyton‐based polyculture systems. The experiment had three treatments: (a) no substrate (control), (b) rice straw as a substrate (3 × 2.7 kg pond?1) and (c) kanchi as a substrate (390 kanchi pond?1). Fingerlings (n=40) of rohu, Labeo rohita (24.5±0.5 g); mrigal, Cirrhinus mrigala (25.1±0.6 g); catla, Catla catla (25.8±0.5 g); common carp, Cyprinus carpio (27.6±0.6 g), and silver carp, Hypophthalmichthys molitrix (30.4±0.9 g) were stocked at a 3:2:2:2:1 ratio and cultured for 90 days. There were no differences in the number of plankton, periphyton and macro‐zoobenthos among the treatments. The total plate count of bacteria was higher in the rice straw treatment (41 320 million cfu m?2) than that in the kanchi treatment (11 780 million cfu m?2). Growth and the final mean weight of rohu, catla and common carp were higher in the substrate treatments than those in the control. Rice straw and kanchi treatment, respectively, resulted in 38% and 47% higher combined total weight gain over control. Gross margin analysis showed that rice straw treatment resulted in more profit than the control and kanchi treatment. Therefore, rice straw has the potential to be used to increase production in the low‐input rural aquaculture.  相似文献   

13.
The effects of three different combinations of silver carp Hypophthalmichthys molitrix and catla Catla catla density on the production system in all‐male freshwater prawn–finfish polyculture ponds were evaluated in triplicate. The stocking density of silver carp and catla, respectively, were maintained at 2000 and 500 ha?1 in treatment SC2000C500, 1500 and 1000 ha?1 in treatment SC1500C1000 and 1000 and 1500 ha?1 in treatment SC1000C1500. Male freshwater prawn Macrobrachium rosenbergii and small fish mola Amblypharyngodon mola densities were fixed in all treatments at 12 000 and 20 000 ha?1 respectively. Management practices were same for all treatments. Blue‐clawed male prawns were harvested twice during the 122‐day culture at 15‐day intervals before the final harvest. Plankton and macro‐benthos abundance and water quality parameters (except transparency and chlorophyll a) did not vary significantly (P>0.05) among treatments. Mean final weights of both silver carp and catla were decreased with the increasing of their own stocking density. The treatment SC1500C1000 resulted in 25–32% increased net production of silver carp plus catla (461 kg ha?1) and 20–21% increased net production of all species combined (874 kg ha?1) as compared with the other treatments, although the differences in production of prawn and mola among treatments were not significant.  相似文献   

14.
Abstract In Sri Lanka, there is a great potential for the development of culture-based fisheries because of the availability of around 12 000 non-perennial reservoirs in the dry zone (<187 cm annual rainfall) of the island. These reservoirs fill during the north-east monsoonal period in October to December and almost completely dry up during August to October. As these non-perennial reservoirs are highly productive, hatchery-reared fish fingerlings can be stocked to develop culture-based fisheries during the water retention period of 7–9 months. The present study was conducted in 32 non-perennial reservoirs in five administrative districts in Sri Lanka. These reservoirs were stocked with fingerlings of Indian (catla Catla catla Hamilton and rohu Labeo rohita Hamilton) and Chinese (bighead carp Aristichthys nobilis Richardson) major carps, common carp Cyprinus carpio L., genetically improved farmed tilapia (GIFT) strain of Nile tilapia, Oreochromis niloticus (L.) and post-larvae of giant freshwater prawn, Macrobrachium rosenbergii De Man, at three different species combinations and overall stocking densities (SD) ranging from 218 to 3902 fingerlings ha−1, during the 2002–2003 culture cycle. Of the 32 reservoirs stocked, reliable data on harvest were obtained from 25 reservoirs. Fish yield ranged from 53 to 1801 kg ha−1 and the yields of non-perennial reservoirs in southern region were significantly (P < 0.05) higher than those in the northern region. Naturally-recruited snakehead species contributed the catches in northern reservoirs. Fish yield was curvilinearly related to reservoir area (P < 0.05), and a negative second order relationship was evident between SD and yield (P < 0.05). Chlorophyll-a and fish yield exhibited a positive second order relationship (P < 0.01). Bighead carp yield impacted positively on the total yield (P < 0.05), whereas snakehead yield impact was negative. Bighead carp, common carp and rohu appear suitable for poly-culture in non-perennial reservoirs. GIFT strain O. niloticus had the lowest specific growth rate among stocked species and freshwater prawn had a low return.  相似文献   

15.
A sustainable semi-intensive pond aquaculture technology including major carp species as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. The inclusion of silver carp (Hypophthalmichthys molitrix), a cheap large species affordable by poor farmers, is now being considered. As part of a study on the effects of this filter feeder on polycultures including the large carps rohu (Labeo rohita), catla (Catla catla) and common carp (Cyprinus carpio) and the SIS punti (Puntius sophore) and mola (Amblypharyngodon mola), an experiment was carried out under farm conditions to test the effects of silver carp and of each SIS species on the growth, survival and yield of the large and small species and on pond ecology.The experiment was performed in 38 farmers' fishponds of different sizes, from 220 m2 to 1200 m2. The results show that the larger the fish pond the better rohu performance, the larger punti fry weight and the lower punti fry harvested biomass. Pond size did not affect other fish species. The addition of 250 mola and/or punti per 100 m2 fishponds affected rohu and catla and did not affect common and silver carps. The addition of mola alone reduced rohu's parameters by 15%. The addition of SIS in the three combinations tested (250 mola, 250 punti, 125 of each species) reduced catla's parameters by 20-24%. Punti fry were larger when both SIS were stocked and punti fry biomass was larger when only punti were present. Total mola harvested biomass and yield were larger when the entire SIS stocked were only mola.The addition of 10 silver carp over the 99 large carps stocked per 100 m2 fishponds negatively affected rohu and catla growth and yield by about 15-21% and 45-50% respectively but not their survival, did not affect common carp performance, did not affect punti and mola reproduction in the ponds, reduced punti yields by 25%, reduced mola performance by about 35%, and silver carp own biomass increased total yield and total income in about 12% each. These effects are explained and discussed considering fish interactions through the food web. The decreased income from selling the more expensive large carps is more than compensated by that obtained from silver carp, which allows the option to the farmer to sell part of the silver carp to complete the cash income that would have been obtained from large carps only if silver carp would not be stocked, and consume the rest with the family.  相似文献   

16.
A polyculture experiment with the large carp rohu, Labeo rohita (Hamilton), catla, Catla catla (Hamilton) and either mrigal, Cirrhinus mrigala (Hamilton) or common carp, Cyprinus carpio (L.) (as cash crop fish), and the small indigenous fish punti, Puntius sophore (Hamilton) (as food for the small‐scale farmer family) was carried out at the Field Laboratory of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh. The main objective was to compare polycultures of large carp in which the bottom feeder is either the native mrigal or the exotic common carp. Secondary objectives were to assess the effects of adding the small indigenous species punti to polycultures of large carp, and to compare the effects of mrigal and common carp on punti production and reproduction. It was found that (i) common carp damaged embankments, had no effect on catla, improved rohu performance by 50% and total fish production by 20%; (ii) punti addition did not affect rohu, catla and total yield, improved mrigal performance by 50%, and decreased common carp performance by 20%; and (iii) punti was not affected either by common carp or by mrigal. However, its performance was not satisfactory, probably owing to frequent netting, which might have hindered growth and breeding. In spite of the embankment damage caused by common carp, this bottom feeder seems to be more promising than mrigal, because it leads to higher fish production. The addition of punti to the large carp polyculture is a viable proposition, as it does not reduce cash crop production, and might be a good food source for a small‐scale farmer's family.  相似文献   

17.
Digestive enzymes of freshwater fish Labeo rohita (family Cyprinidae; class Actinopterygii; infraclass Teleostei; order Cypriniformes) were studied during ontogenic development. Amylase, protease and lipase activities showed a polynomial relationship with age of rohu, whereas trypsin, chymotrypsin and lipase activities exhibited exponential trends with the age of rohu larvae. SDS‐PAGE of crude enzyme extract revealed that the proteases of higher molecular weight (MW) appeared during early ontogeny, whereas low MW proteases were observed at a later stage. Substrate SDS‐PAGE supported the quantitative study of protease activities as evidenced with the increasing number and intensity of activity bands with the age of fish. The number of protease activity bands observed in 4, 10, 12 and 24 DAH (days after hatching) larvae were 5, 7, 8 and 9, respectively. Inhibition of protease activities with soybean trypsin inhibitor (SBTI) (58.6–81.2%), phenyl methyl sulphonyl fluoride (PMSF) (55.6–70%), N‐α‐p‐tosyl‐l ‐lysine chloromethyl ketone (TLCK) (41.1–52.3%) and N‐tosyl‐l ‐phenylalanine chloromethyl ketone (TPCK) (27.9–44.5%) indicated the presence of serine proteases, trypsin‐ and chymotrypsin‐like enzymes in rohu larvae. Inhibition with SBTI and TPCK showed power, TLCK and ethylenediaminetetraacetic acid showed exponential, whereas PMSF showed polynomial relationships during the study period.  相似文献   

18.
Isolation and enumeration of phytase‐producing bacterial flora in the foregut and hindgut regions of the gastrointestinal tracts of 10 culturable freshwater teleosts of different feeding habits, namely rohu (Labeo rohita), catla (Catla catla), mrigal (Cirrhinus mrigala), bata (Labeo bata), kalbasu (Labeo calbasu), Nile tilapia (Oreochromis niloticus), climbing perch (Anabas testudineus), common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix) and grass carp (Ctenopharyngodon idella), have been carried out. Microbial culture of the gut mucosa on selected nutrient media following the enrichment culture technique was performed for bacterial isolation. The bacterial isolates were screened on the basis of their enzyme‐producing ability. The bacterial population on the tryptone soya agar (TSA) plate was maximum in the hindgut region of bata, followed by mrigal and minimum in the foregut region of Nile tilapia. In modified phytase screening medium (MPSM), phytase‐producing strains were recorded at higher densities in the foregut region of mrigal and grass carp and minimum in the foregut region of bata. In case of the hindgut, maximum phytase‐producing strains were present in grass carp and mrigal and minimum in rohu. In general, in MPSM, the bacterial population was lower in the hindgut region of all the 10 species of fish examined. The phytase‐producing ability of the selected 31 strains (16 from the foregut and 15 from the hindgut region) was determined by clearing zones on phytate‐containing plates. Among these isolates, 22 strains (12 from the foregut and 10 from the hindgut region) were selected as potent phytase producers according to a quantitative enzyme assay. The highest phytase activity was observed in the bacterial strains LF1 and LH1 isolated from the fore and the hindgut regions of rohu respectively. Both the strains were identified as Bacillus licheniformis on the basis of phenotypic characteristics as well as 16S rDNA sequence analysis.  相似文献   

19.
A sustainable semi-intensive pond aquaculture technology including major carp species (Indian, Chinese and common carp) as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. Silver carp inclusion in the polyculture is now being considered, because this very efficient filter feeder has a strong impact on pond ecology and also on the farmers' family nutrition because it is a cheap fish that the family can afford to eat instead of selling. The present paper is centered on the reduction of silver carp negative effects on other species while keeping the advantages of increased total yield and income due to silver carp stocking. It presents the results of two experiments, one on-station and one on-farm, in which 3–5 silver carp/100 m2 were added or partially substituted major carp filter feeders. The basic stocking density was 100 carps (rohu, catla and a bottom feeder, either mrigal or common carp, at a 1:1:1 ratio) and 250 SIS (punti and mola) per 100 m2. In the on-station experiment silver carp density was 3 and 5 fish/100 m2 and the large carp bottom feeder was common carp. In the on-farm experiment silver carp density was 5 fish/100 m2 and the bottom feeder was either common carp or mrigal.Most of the water quality and fish performance parameters tested were not affected by the polyculture composition. Adding 3–5% silver carp or substituting 3–5% of the herbivorous fish species by this highly efficient filter feeder increased grazing pressure on the phytoplankton, which led to a 25–40% reduction of the chlorophyll concentration in the water column. The increased grazing pressure was not enough to affect other water quality parameters and fewer effects on the availability of food for the other fish species occurred than when the silver carp addition was 10% of the polyculture, as reported in a previous work. The strong negative effects of silver carp on the other species of the polyculture and the higher total yields and income recorded in previous experiments with the addition of 10 silver carp/100 m2 were much weaker and their expression depended on other pond conditions when 3 or 5 silver carp/100 m2 were added or substituted the same number of rohu or catla, either when the bottom feeder was mrigal or common carp. It was concluded that stocking 3 silver carp/100 m2 over the usual 100 large carp and 250 SIS /100 m2 can be considered a ‘no effect’ stocking density in relation to the control without silver carp, while stocking 10 silver carp/100 m2 should be preferred by farmers to keep the option of selling or consuming the silver carp.  相似文献   

20.
Abstract. The fry of four species of planktivorous carp, silver carp, Hypophthalmichthys molitrix (Valenciennes), bighead carp, Aristichthys nobilis (Richardson), rohu, Labeo rohita (Hamilton), and catla, Catla catla (Hamilton), were grown in monoculture in ponds in Mymensingh, Bangladesh in order to determine electivity and the extent of dietary overlap. Other than an avoidance for Cyanobacteria, electivity was found to be low in most instances, although the low productivity of the ponds may have had some influence. Dietary overlap was greatest between catla and silver carp (0–52) and between catla and bighead carp (0–48).  相似文献   

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