Larval rearing of a freshwater prawn Macrobrachium gangeticum

Observations were made on the larval development of a freshwater prawn, Macrobrachium gangeticum, which revealed that hatching occurred in freshwater but the larvae failed to survive after 2nd molting. Salinity was necessary for survival of the larvae after 2nd molting. The complete larval development involved nine larval stages and the 10th stage was considered to be the post-larva which measured between 4.5 and 5.0 mm in length. All the larval stages were completed within 26 days of hatching. Specimens from each larval stage were taken out and examined under a microscope.

Analysis of lipid and lipid-fractions of some freshwater fishes and their inter-relationship

Two fish species each from carnivorous (Clarias batrachus, Channa punctatus), omnivorous (Cyprinus carpio, Cirrhinus reba), and plankton feeder (Catla catla, Labeo rohita) were collected from freshwater sources under natural habitat to study their total lipid (TL) and lipid-fractions. Significant relationship between these parameters was also worked out. The variation of total lipid and lipid-fractions in tissues of freshwater fishes were not significantly different (P>0.05). But a higher trend of total lipid and glyceride (TGL) contents were found in carnivores followed by omnivores and least in plankton feeders. The trend was reverse for total phospholipid, cholesterol and free fatty acids. TGL content in all class of fishes was significantly related with TL (P<0.01), phospholipid (PL) (P<0.001), cholesterol (P<0.05), free fatty acids (P<0.05) and monoglycerides (P<0.001). Similarly total lipid was linearly related with total glycerides (TL=-3.02 + 0.10 TGL) and phospholipid (TL=7.13-0.12 PL). From this study it is concluded that almost all lipid-fractions of freshwater fishes can be predicted easily from total lipid content of the tissue.

Growth of juvenile freshwater prawn Macro brachium mslcolmsonii fed with various protein diets containing different biowastes

An experiment was conducted with juvenile prawns Macrobrachium malcolmso11ii, (0:76± 0.01 ro 0.94-::tO.Ol g) w evaluate various protein source diets. Six diets containing 20%, 25%, 30%, 35%, 40%,and 45% of crude protein were formulated, and fed to prawns in the form of pellet to evaluate their suitability. The experiment was designed for 60 days and sampling was made at every 15 days interval. At the end of the study period growth, feed conversion ration (FCR) specific growth rate (SGR), feed efficiency and survival were determined for prawns in each dietary treatment. Among the above five feeds poor FCR and higher weight gain observed in 35% protein diet (B-4). Similarly specific growth rate and feed efficiency are also highest with diet containing 35% protein. The dietary protein levels above 35% exerts a decrease in growth of prawn was observed in the present study. The feed efficiency ratio and protein efficiency ratio decreased with the increased dietary protein levels. It is concluded that 35% protein diet could be suitable with optimum protein supply for Macrobrachium malcolmsonii Therefore, above and below this 35% protein level in the formulated feed leads to metabolic stress which lowers the conversion efficiency and wastage of nutrients.

Effect of high and low cost brood feeds on gonado-somatic index and fecundity of freshwater prawn Macrobrachium rogenbergii de Man

Studies were conducted to observe the effects of different types of feeds on the gonado-somatic index (GSI) and fecundity of freshwater prawn Macrobrachium rogenbergii. Three different treatments (T1 T2 and T3) were designed with three types of feed as follows: (i) Saudi-Bangla Prawn feed 100% - T1 (ii) SaudiBangla prawn feed 50%+ local feed 50%- T2 and (iii) local feed 100%- T3. The results showed that the average value of gonado-somatic index (GSI) was 14.39, 14.35 and 14.36 and the average fecundity of M. rogenbergiiwas 99,741, 98,125 and 97,911 in T1 T2 and T3 respectively. No significant difference (p>00.5) was between gonado-somatic indices (GSI) and fecundities of M. rogenbergii among different feeding trails. The price of Saudi-Bangla prawn feed was very high (Tk. 23/kg) than the local feed (Tk. 14/kg). So, use of local feed was recommended for M. rogenbergii brood rearing.

Use of crude salt in rearing of freshwater giant prawn, Macrobrachium rosenbergii (de Man) larvae

Three different types of culture media: (i) 100% brine (B 100 ), (ii) 75% brine and 25% crude salt (B 75 CS 25 ), and 50% brine and 50% crude salt (B 50 CS 50) were tested to evaluate the possible use of brackish water reconstituted from the crude salt for the production of M. rosenbergii post-larvae. The production rate of 25.26±0.20 PI/l with a corresponding survival rate of 84.20±0.66% was significantly higher (P<0.05) for the larvae reared on B100 than that of 22.10±0.57 Pl/l with a corresponding survival rate of 73.68±1.89% on B50CS50. Larvae cultured on B75CS25 did not show any significant difference (P<0.05) in production as well as in survival of post-larvae than that on B100. The result shows that, for rearing of prawn larvae, use of brine can be replaced up to 25% without any undue reduction in production of post-larvae. However, the production as well as survival rate of post-larvae with 50% replacement (B50CS50) is also appreciable. It is assumed that the mineral constituents of natural seawater might have some triggering effects on prawn larvae in closing their larval cycle.

Incidence of epizootic ulcerative syndrome (EUS) in freshwater fishes in the endemic area of Punjab, Pakistan

Incidence of Epizootic Ulcerative Syndrome (EUS) has been recorded for the first time in freshwater fishes in the endemic area of Punjab, Pakistan. Survey of private fish farms, hatchery and natural water bodies was conducted in a radius of 14 Km from around river Ravi near Lahore (Punjab Province) Pakistan. Out Of 1628 fishes belonging to 18 genera, 517 fishes of 10 genera were found affected with EUS. The incidence of EUS in culturable fishes was higher in Cirrhina mrigala (15.4%) moderate in Catla cat/a (13.3%) and lower in Labeo rohita (5.0%). Exotic fish, Chinese carp Ctenoparyngodon idella and Hypophthalmicthys molitrix were not affected with EUS. In non-culturable fishes the incidence of EUS was highest in Channa punctatus (72.8%) moderate in by C. straitus (65.45%) and comparatively lower Puntius ticto (43.7%). A slow growing temperature sensitive Saprolegnia spp. was isolated from all of EUS infected fish species. Aeromonas spp. and Pseudomonas spp. were isolated from the diseased fishes. Ectoparasites viz. Lernaea, Argulus and Triclwdina spp. were also isolated from the skin and gills of infected fish species. The disease was more severe in water having low alkalinity (70 mg/1), hardness (75 mg/1) and low temperature of 10-12 °C.

The potential of mixed culture of freshwater giant prawn Macrobrachium rosenbergii de Man and tiger shrimp Penaeus monodon Fab. at Khulna region, Bangladesh

The freshwater giant prawn (golda), Macrobrachium rosenbergii and tiger shrimp (bagda), Penaeus monodon were stocked together with or without fin fishes at different stocking rates in semi-saline waters at Khulna region and their growth, survival, yield and costreturn analysis were made. Survival rate of golda and bagda ranged from 23.0 to 36.8% and 8.2 to 24%, respectively. The both species were significantly affected by their own stocking density. The average final weight of golda and bagda ranged from 62.4 to 73.3 g and 32.0 to 66.4 g. The bivariate analysis of average final weight of both golda and bagda revealed that golda positively and bagda negatively influenced by the total stocking density. However, the results of the individual sizes of both golda and bagda showed an increase in the proportions of smaller animals and a decrease in the proportion of larger ones with increasing stocking rates. The harvesting weights of all animals in the experimental ghers were in marketable sizes although their prices varied with the individual size. The total production comprised of both golda and bagda ranged from 514.6 to 952.8 kg ha·1, over a culture period of 10 months. Return on investment ranged from 51.0 to 125.7%.

Reproductive biology, artificial propagation and larval rearing of two freshwater eels, Monopterus cuchia and Mastacembelus armatus

Studies on reproductive biology and artificial propagation including larval rearing of freshwater mud eel, Monopterus cuchia and spiny eel, Mastacembelus armatus were attempted. The gonadosomatic index (GSI) of mud eel ranged from 0.41 (August) to 5.52 (June) in males and 0.53 (August) to 7.61 (June) in females. In both cases the GSI showed a peak in June. Fecundity ranged from 228 (TL - 396 mm; W - 78g) to 5510 (TL - 865 mm; W - 630 g). In case of spiny eel, the GSI varied from 0.65 (August) to 8.30 (July) in males and 0.70 (August) to 10.46 (July) in females. GSI showed single peak in July. Fecundity ranged from 570 (TL - 240 mm; W - 30 g) to 10870 (TL - 601; W - 350g). Histology of the testes and ovaries of the eels were carried out to investigate the gonadal development stages during the reproductive months (August to November 2003). In case of male M. cuchia, the secondary primordial germ cells, primary spermatogonium, some spermatogonia A and clone of spermatogonium B in testis were observed in September. In October-males different sized lobules having spermatogonia, spermatocytes and spermatids were observed. In the ovary of M. cuchia, polygonal shaped oocytes were seen during September. The oogonia were reduced with dense and irregular shaped during October. Numerous pycnotic cells were visible during November. In male M. armatus numerous broken lobule walls were found in testes during September. In October, abundant primary germ cells, pycnotic nests of degenerating cells, spermatogonia and spermatids were observed. In females, ovaries had distinct yolk vesicles stage and yolk granules stages in August. In September, the follicular cells of the oogonia were ruptured, shrunk forming irregular shaped in October. Oogonia were also shrunk with thin, irregular shaped structure but broken parts of the ruptured follicular cells were scattered in case of M. armatus. Experimental attempts on artificial propagation indicated that both freshwater eels were difficult to breed using inducing agents like pituitary glands (PG) of 10, 20, 50, 100 and 150 mg per kg of body weight. Same doses were used for both sexes with equal sex-ratio. In both cases, brood fish died at higher doses of injection given at 100 and 150 mg PG/kg bodyweight. However, M. cuchia breed naturally in cisterns when provided with water hyacinths and tunnel in muddy bottom. M. cuchia fed with chopped cooked fish attained a mean weight of 18.75 ± 2.3 g and cent percent survival. While in case of M. armatus best growth by weight (12.0 ± 2.48 g) and cent percent survival were achieved using chopped raw fish. Car tyre was observed as best shelter for attaining the mean weight gain 22.53 ± 2.24 g and cent percent survival of M. cuchia. While PVC pipe was found to be the best shelter for M. armatus, where it attained the mean weight of 12.73 ± 1.88 g and cent percent survival.

Influence of stocking density on the culture potential of freshwater catfish Pangasius pangasius in pond

Influence of stocking density on the production of freshwater catfish Pangasius pangasius with formulated feed in ponds was studied. The fish fry were collected from the Meghna river near Chandpur which is a natural breeding ground of this fish. Three stocking densities chosen during this experiment were 5000, 8000 and 11000 fry/ha with an initial weight of 42.57 ±2.51 g. The formulated feed was prepared in the laboratory which contained 45% fish meal, 30% mustard oil cake, 15% wheat bran and 10% rice bran to supply 40.48% protein in feed. The growth of P. pangasius in terms of net weight gain was 409.49, 266.49 and 236.37 g at the 5000/ha, 8000/ha and 11000/ha stocking densities respectively, which was statistically significant (p<0.05). High food conversion ratio (FCR) was also observed during this research study which ranged between 7.06 to 7.72. A production of 2.6 tons/ha at the stocking density of 11000/ha; 2.13 tons/ha at the stocking density of 8000/ha and 2.04 tons/ha at the stocking density of 5000/ha was obtained, while the growth of individual fish at the end of experiment was in opposite order. The result of this experiment indicates that stocking density has significant influence on the culture potential of freshwater catfish P.pangasius.

Selection of freshwater pearl mussel species for mantle transplantation in Bangladesh

Allograft mantle transplantations were studied in six species of freshwater mussels~ Lamellidens marginalis, L. corrianus~ L. jenkinsianus_, L. phenchooganjensis~ Parreysia corrugata and P. favidens by transplanting foreign mantle tissue into the mantle tissue of a host mussel. After three months of rearing, maximum survivability and pearl formation were observed in L. marginalis and L. jenkinsianus followed by L. corrianus and L. phenchooganjensis. Very poor results were observed in case of Parreysia corrugata and P. favidens. In addition to the natural pearl producing capacity of individual species, survivability and pearl production were related to the size of the mussel species. L. marginalis has been identified as the best species for mantle transplantation in Bangladesh.

Polyculture of freshwater prawn, Macrobrachium rosenbergii, de Man with carps: effects of prawn stocking density

Effects of three stocking densities, viz., 35, 50 and 65/decimal (1 decimal = 40.48 m2) of juvenile freshwater prawn (Macrobrachium rosenbergii) on prawn and fish production were tested in a polycuture system with silver carp (Hypophthalmichthys molitrix), catla (Catla catla), Grass carp (Ctenophmyngodon idella) and silver barb (Barbodes gonionotus). The fish stocking density was 19/decimal with the species combination of silver carp-10, catlac-6, grass carp-1 and silver barb-2. In a 8-month culture period, the prawn yield 423 ± 144 kg/ha was significantly lower (P< 0.5) with the prawn stocking density of 35/decimal than that of 548 ± 178 kg/ha and 662 ± 243 kg/ha with 50 and 65/decimal respectively. The fish production (1844-1891 kg/ha) did not differ significantly (p <0.05) among the three treatments indicating that prawn stocking densities had no influence on fish yield. The lower mean harvest weight (62 g) and survival rate (67 g) and higher yield (2.67 kg/decimal) with the highest stocking rate of prawn reveals that as density was increased, prawn survival and individual weight at harvest decreased but total yield increased.

Development of low cost feed using local ingredients for culture of freshwater prawn, Macrobrachium rosenbergii in ponds

Two experiments were conducted to formulate and evaluate test diets using locally available ingredients to find out suitable diets for mono and polyculture of Macrobrachium rosenbergii in ponds. The first experiment was conducted from 1 July 2003 to 29 September 2003 in 12 experimental ponds each measuring 30 square meters behind the Fisheries Faculty Building, BAU campus, Mymensingh. Three experimental diets containing 30% protein were formulated using fish meal, meat and bone meal, mustard oilcake, sesame meal and rice bran and assigned to treatments 1, 2 and 3, respectively. A special shrimp feed (Starter-II) from Saudi-Bangla Fish Feed Ltd. was assigned to treatment 4 (Control). Each treatment had three replications. Juveniles of M. rosenbergii (2.90±0.81g) were stocked at the rate of 4/square meter. Prawns were fed three times daily at the rate of 15% of their body weight at the beginning, which was gradually reduced to 10% and 5% for the last two months. There was no significant (P>0.05) difference between the weight gains of prawns fed diets 1 and 4 (control), but they were significantly (P<0.05) higher than those of diets 2 and 3. The FCR values of diets ranged between 2.61 to 3.36 with diets 1 and 4 showing significantly (P<0.05) lower FCR values. The survival rate of prawns ranged between 68 to 78% with prawns fed diets 1 and 4 showing significantly higher survival rate. The production of prawn ranged from 921 to 1,428 kg/ha/90 days and diet 1 gave the highest production. Treatment 1 gave the highest net profit ofTk. 161,980/ha/90 days. The second experiment was conducted from December, 2003 to April, 2004 to see the growth of over wintered M. rosenbergii juveniles in polyculture with indigenous major carps (catla and rohu) in ponds using formulated diets. Three isoenergetic experimental diets formulated using fish meal, meat and bone meal, mustard oil cake, rice bran, wheat bran and molasses, and a shrimp feed 'Golda special feed' from Saudi-Bangla Fish Feed Ltd. were assigned to treatments 1, 2, 3 and 4 (control), respectively, each treatment had two replications. Eight experimental ponds each measuring 80 square meters in the Field Laboratory Complex of the Faculty of Fisheries, BAU campus, Mymensingh were used. The mean initial weights of M. rosenbergii, catla and rohu were 1.60±0.01, 30.0±0.09 and 25.0±0.08 g, respectively. A total of 160 fish and prawn (20,000/ha) were stocked in each pond at the ratio of 2:1:1 (prawn: catla: rohu). Fish were fed at the rate of 3-5% of their body weight. Prawns fed diet 1, 2 and 4 showed higher weight gains compared to diet 3. The weight gain of catla was significantly higher in T1 while in case of rohu was higher in T1 and T4, respectively. There were no significant differences (P>0.05) in the survival rate of fish as obtained from different treatments. The overall total fish production ranged from 2196 to 2679 kg/ha/5 months. The highest production and the highest profit (Tk. 56,531/ha/5 months) was obtained from T1 and the lowest (Tk. 24,932/ha/5 months) from T4.

Selective biochemical studies in a freshwater prawn, Macrobrachium nobilli(Crustecea: Palaemodinae)

Calcium and phosphorous contents of abdomen and cheliped muscles of juvenile, male and female Macrobrchium nobilii were determined from field collected samples. In all the three groups calcium concentration was higher in chelipeds while the phosphorous content was more in abdomen muscles than in the chelipeds. However between three groups the calcium content varied significantly both in the abdomen and cheliped muscles (P

Present status of harvesting, transportation and marketing of freshwater Small Indigenous Species of Fish (SIS) of Bangladesh

A survey conducted to evaluate the present status of harvesting, transportation and marketing of freshwater SIS of Bangladesh showed that among the 56 to 73 species of small indigenous fish species (SIS), mola (Amblypharyngodon mola), dhela (Osteobrama cotio cotio), puti (Barbodes sarana), tit puti (Puntius ticto), tengra (Mystus vitatus), chapila ( Gudusia chapra), batashi (Pseudotropius atherinoides), buzuri tengra (Mystus tengra), katchki (Corika soborna), gol chanda (Chanda ranga), lamba chanda (Chanda nama), phul chela (Chela phulo) and lata (Channa punctatus) are the most common. But the abundance of the mola, puti, tengra, batashi and chapila are higher than the other SIS species. Puti was at the top of the list in percentage abundance (7-9%), followed by mola (7-8%), tengra 6-7% and chapila 5-6% in all the investigated areas. Three levels of market or marketing systems were observed in the distribution channel of fish trade: primary, secondary/higher secondary and final consuming markets. Primary market is the catching point in the rural area. In secondary market, the collectors bring the fish from primary market to the landing ghats, usually to the nearest thana market or at a place well linked by rivers, road and rail transport. On purchasing the fish from the higher secondary market, the paikars sell the fish to the retailers who take it to the final consumer market. Different types of crafts and gears are used for catching the SIS in Bangladesh. Monofilament gill nets (20%), traps and line nets (25%) and seine nets (25%) are the dominant gears in respect of the total catch followed by lift net (10%) and cast net (20%). A total of 10 types of gear are listed according to their mode of operation which used for catching SIS. The processors in consumer market received higher marketing profit followed by primary market and secondary market, respectively.

Effect of delayed icing on quality changes and shelf-life of some freshwater fish from Bangladesh

The quality and shelf-life of three freshwater fish species of Bangladesh, catla (Catla catla), magur (Clarias batrachus) and tilapia (Oreochromis niloticus) stored at room temperature and ice were evaluated. Live fishes were killed by cranial spiking and stored at room temperature (27-30 °C), ice stored immediately after death, 5 hr after death and 10 hr after death. The shelf-life and quality of the fishes were evaluated by organoleptic method, rigor-mortis studies and bacteriological assessment. Fishes kept at room temperature became organoleptically unacceptable within 16-20 hr duration. Ice stored fishes showed considerable differences in their shelf-life when icing was delayed for different duration. Shelf-life of catla ice stored immediately after death was 20 days but shelf-life reduced to 12 days when icing delayed for 10 hr after death. Similar trend was observed for two other fish species magur and tilapia. Rigor-index of the fishes stored under different conditions also considerably varied among the three fish species, particularly effect of delayed icing was very much evident. Bacteriological study showed patterns of Aerobic Plate Count (APC) at the end of shelflife study when fishes became organoleptically unacceptable were more or less similar for all the three fish species stored under different conditions. No definite pattern was observed in the generic distribution of bacteria in different fish species under different storage conditions. Micrococcus, Coryneforms, Pseudomonas and Achromobacter were the dominant groups of bacteria isolated from the fishes spoiled at room temperature and ice stored condition.