Acclimatization of juveniles of marine prawn Penaeus monodon to fresh water

Penaeus monodon, hitherto cultured in brackishwater, has been acclimatized to fresh water for culturing in fresh water system. One hundred juveniles of P. monodon measuring in an average 27.7 mm were procured from the coastal lowlying areas near Kakinada in Andhra Pradesh and were used to conduct an experiment on acclimatization. High percentage of survival (96.0%) was observed when the water salinity was lowered gradually at the rate of 10% per day for the first 2 days, 5% per day during the next 2 days and later at the rate of 1% per day.

Comparison of growth and conversion efficiency of the freshwater prawn Macrobrachium malcolmsonii (H. Milne Edwards) juveniles fed with formulated and commercial feeds

A nutritional study was carried out to know the feasibility of formulated and commercial feeds on the growth of juveniles of the freshwater prawn Macrobrachium malcolmsonii. Best relative growth rate was observed for feed 1 followed by feeds 2 and 3. Animals fed with feed 1 showed higher production than the other feeds. Higher assimilation efficiency was noticed in the animals provided with feeds 5 and 4. Higher gross and net growth efficiencies were observed in the animals offered feed 1. Among the commercial feeds, feed 3 may considered to be suitable alternative to feed 1.

Use of length-weight relationship in grading processed beche-de-mer

Holothurians, belonging to the species Holothuria scabra, have been collected by diver-fishermen and processed for export. There is an active fishery for these animals in Palk Bay and Gulf of Mannar, off the north-western coast of Sri Lanka. The absence of standardized method of grading has led to unwarranted variation in sale prices and sometimes in loss of foreign exchange in Sri Lanka. In this paper an attempt is made to present a method to grade processed beche-de-mer by using the lenght-weight relationship.

Effect of feeding three different formulated feeds having different protein levels on the growth of angel fish (Pterophyllum scalare) juveniles

Experiment was conducted to study the effect of dietary protein level on growth and nutrient utilization by angel fish (Pterophyllum scalare) juveniles. Fifty-four juveniles (average wt. 2-2.5 g) were equally divided in three treatments with each of three replicates. Three formulated diets with graded protein levels, T1 (35% CP), T2 (40% CP) and T3 (45% CP) were fed to juveniles for 45 days. A trend of higher weight gain %, SGR, FER and PER was found with the increased CP level in the feed. Feed intake was similar in all the groups. T3 group fed with 45% CP registered highest weight gain % (43.26 ± 2.07), SGR (0.78 ± 0.04), FER (0.29 ± 0.01), which were significantly higher (P<0.05) than the T1 and T2 groups. Protein digestibility of T2 and T3 groups was significantly higher than the T1 group. Survival was similar in all the experimental groups. Diet with 45% CP with protein energy ratio of 112.62 mg protein/K cal. is ideal for juvenile angel fish for indoor rearing.

Production of freshwater giant prawn using over-wintered juveniles for enhancement of farm income and reduction of rural poverty in Bangladesh

Freshwater giant prawn, Macrobrachium rosenbergii fry produced during late season can not withstand low temperature thus the prawn culture programme during winter is hampered. To overcome this problem, late season (August-September) prawn juveniles (0.9-6.8 g) were stocked at a density of 1.43 to 3.57/square meter in 350-476 square-meter ponds in Pabna and Mymensingh districts during October 2000 and cultured till May 2001. Monthly average water temperature during the winter months (December-February) varied from 16 to 22 °C and gradually increased to 32 °C in May. The prawn fry showed fast growth rate and attained an average weight of 60-70 g within eight months including three winter months. Growth compensation was observed during summer months. Survival rate was 60-79%. After extrapolation of the present growth rate more than 1,600 kg/ha production can be achieved in better-managed ponds. Extrapolated cost of production was Tk. 268,000 and 200,000 Tk./ha in two best ponds, sale value was Tk. 644,9146 [sic] and 528,466 and gross profit was Tk. 376,000-410,000, suggesting a higher economic feasibility of farming freshwater prawn with over-wintered juveniles.

Mass production of Penaeus monodon Fabricius juveniles in earthen nursery ponds

Different culture techniques were tried for rearing larvae of Penaeus monodon, in order to obtain preliminary data on stocking density, water management, fertilization versus feeding and effect of different types of vertical substrate. The results of the experiments showed that: (1) older fry have greater chances of survival; (2) the traditional nursery pond designs and practices used for milkfish in the Philippines are applicable to prawn only at very low densities and give acceptable high survival rates only when used with the older postlarval stage.

Survival and changes in the fine structure of selected tissues of Penaeus monodon Fabricius juveniles fed various carbohydrates

Penaeus monodon juveniles were reared on semipurified diets containing various carbohydrates (maltose, sucrose, dextrin, molasses, cassava starch, corn starch or sago palm starch). Significant differences were observed between the type as well as the level of carbohydrate in the diet on the survival of the juveniles. Results indicate that there does not seem to be any correlation between survival and the complexity of the carbohydrates.

Transport of sugpo, Penaeus monodon juveniles

This study was made as an attempt to investigate the optimum packing density and the ice quantity suitable for the transport of Penaeus monodon juveniles. The results revealed that prawns of 40 mg size can be packed to as much as 3,000 per bag. While packing densities above 3,000 per bag containing 8 L seawater and 16 L oxygen can be used only for short transport periods. On the other hand in the ice-quantity experiment, mortality rate was less than 1% in all the bags containing 300 g, 600 g, 900 g and 1200 g of ice. A packing temperature of 20~’C must be maintained hence, 50 g of ice per hour should be allowed per box, counting from the moment the box is sealed to the time it is estimated to be opened.

Optomotor reaction of milkfish larvae and juveniles

The development of the optomotor reaction (OMR) in milkfish (Chanos chanos), from the larval, through the metamorphic, to the juvenile stage was observed. The period from the appearance of the pelvic fins until the complete disappearance of the finfold was named ”metamorphic stage”. While the larvae showed strong rheotactic responses, their OMR was somewhat weak. It was clear that the OMR underwent a big change through the metamorphic stage, and became strong and almost perfect in the juveniles.

A comparative study on effects of Immunoster and Immunowall as immunostimulants on some hematological, biochemical and growth indices of farmed great sturgeon juveniles (Huso huso)

Prebiotics are non-digestible food ingredients that profitably affect the host by selectively stimulating the growth and /or activation of one or a limited number of bacteria in the intestine that can enhance host health status. Immunoster (IS) and Immunowall (IW) are prebiotics and immunostimulants derived from the outer cell wall of brewers yeast, Saccharomyces cerevisiae. These substances contain MOS and �-glucans. After a four-week acclimatization period to rearing conditions and basal diet, 450 farmed great sturgeon juveniles weighing 95.58 ± 9.38 g were randomly distributed into 15 fiberglass tanks (2 × 2 × 0.53 m) in five treatments (Control, IS 1%, IW 1%, IS 3%, and IW 3%) in three replicates (completely randomized design) and kept at a density of 30 fish per tank for a period of 8 weeks at water temperature 20.55 ± 5.11ºC, dissolved oxygen 6.73 ± 0.35 mg L-1 and pH 7.92 ± 0.09. IS and IW were added at two levels of 1% and 3% to the basal diet in place of cellulose, except the control. At the beginning, in the middle and at the end of the trial, carcass analysis was done to determine the moisture, protein, fat, ash, and total carbohydrate. Also, blood samples were collected to measure hematological, biochemical and immune indices. At the end of the trial, final weight, final length, body weight increase (BWI), specific growth rate (SGR), average daily growth (ADG), protein efficiency ratio (PER), feed conversion ratio (FCR), and condition factor (CF) in fish fed on IS and IW in both levels 1% and 3% showed some differences. These differences were significant in IS 3% and IW 1% and 3% compared with the control (P<0.05). HSI showed no significant difference (P>0.05) and survival rate was 100% in all treatments. Crude protein of carcass in fish fed on IS and IW at 1% and 3% showed an increase in comparison with the control. There was significant difference between IS 3% and the control in crude protein of carcass (P<0.05). Fish fed on IS and IW at 1% and 3% showed various results in hematological and biochemical factors. It was observed significant difference in MCV between IW 1% and IS 3% compared with the control (P<0.05). Although there was an increase in values of hematocrit, hemoglobin (except IS 1%), WBC (except IW 3%), MCH, neutrophil, total protein, albumin (except IS 3%), K+, and lysozyme in fish fed on IS and IW compared with the control, it was no significant (P>0.05). The maximum count of WBC and the highest value of Ca2+ were seen in IW 1%. The maximum count of lymphocyte, the highest values of total protein, albumin and IgM were recorded in IW 3%. IS 1% had the maximum count of neutrophil and the highest concentration of lysozyme. Based on obtained results, it can be declared that IS and IW at two levels of 1% and 3% can enhance growth performance and feed efficiency and also improve some hematological, biochemical, and immune indices in farmed great sturgeon juveniles.