Diseases have been recognized as the major obstacle to the shrimp ( Penaeus monodon ) and prawn ( Macrobrachium rosenbergii ) aquaculture production in Bangladesh. This study provides an assessment of shrimp and prawn diseases/syndromes, health management practices, and occupational health hazards associated with the handling of chemical and biological products to prevent and treat shrimp and prawn diseases. A survey was conducted using a semi-structured questionnaire with 380 shrimp and prawn farmers in the southwest of Bangladesh during February and June of 2016. The farms were categorized on the basis of the three cropping patterns: shrimp polyculture, prawn polyculture, and shrimp and prawn polyculture. Eight different diseases and/or symptoms were reported by the surveyed farmers. The white spot disease and the broken antenna and rostrum symptom were the most common in shrimp and prawn species, respectively. In total, 35 chemical and biological products (4 antibiotics, 15 disinfectants, 13 pesticides, 2 feed additives and probiotics) were used to treat and/or prevent diseases in the all farm categories. The major constraints for disease management were limited access to disease diagnostic service, inadequate product application information and lack of knowledge on better management practices. Handling chemicals and preparation of medicated feed with bare hands was identified as a potential occupational health hazard. This study suggests improvements in farmers’ knowledge and skill in disease diagnostics and health management practices, and appropriate handling of potentially hazardous chemicals.

The Monsoon River prawn, Macrobrachium malcolmsonii (Milne-Edwards, 1844), is one of the dominant benthic species in the Ganges River. Our study describes some biological parameters including sex ratio, lengthfrequency distributions (LFD), length-weight relationships (LWR), and relative-condition (K n ) factor of M. malcolmsonii in the lower part of the Ganges River, northwestern Bangladesh. A total of 502 specimens of the ranges 3.54-11.76 cm total length and 0.50-15.20 g body weight were analyzed in this study. Sampling was done using traditional fishing traps (Kara) during the period from March to October 2010. The overall sex ratio showed no significant differences from the expected value 1:1 ( 2 ¼ 0.20, p ¼ 0.157), and there was no significant difference in the LFD between the sexes (p ¼ 0.460). The allometric coefficient b for the LWR indicated isometric growth ($3.00) in males and negative allometric growth (53.00) in females. K n showed significant variation (p 5 0.01) between the sexes, with better performance by females (1.027 AE 0.107) than males (0.968 AE 0.130). To our knowledge, this study presents the first comprehensive description of life-history traits for M. malcolmsonii from Bangladeshi waters. Our data should be useful for the sustainable management of this prawn fishery in the Ganges River basin of Bangladesh and neighboring countries.

The aim was to assess the efficacy of prophylactic health products (PHPs) on shrimp (Penaeus monodon) post larvae (PL) during the nursery phase. This included five treatments: infeed probiotic (F_PRO), water probiotic (W_PRO), a combination of water and infeed probiotic (FW_SYN), biofloc, a combination of biofloc and infeed probiotic (F_PRO&biofloc), and a no‐treatment control, five replicates each. Each tank was filled with 450 L water and stocked with 700 PL15, weight 0.008 ± 0.00 g at a density of 1.56 PL/L, reared for 27 days. There were no significant differences in water temperature, dissolved oxygen, alkalinity, and total ammonia nitrogen among treatments and control. pH and nitrite were lower in biofloc and F_PRO&biofloc compared to other treatments. The final body weight, weight gain, specific growth rate and food conversion ratio were significantly higher (p ≤ .05) in F_PRO&biofloc compared to other treatments and control. A salinity stress test showed a significantly higher survival rate in F_PRO&biofloc followed by biofloc than other treatments and control. Our study indicated that rearing shrimp in biofloc alone or combined with infeed probiotic might increase growth and resistance to environmental stressors. Further on‐farm trials are required to confirm the efficacy of the PHPs.

Intensive shrimp (Penaeus monodon) production system is relatively new in Bangladesh, and has not yet been adequately described or its viability assessed. The aims of this study were to characterize, assess the economic performance and identify challenges for intensive shrimp farming in Bangladesh. A survey was conducted using a structured questionnaire enumerated between October 2016 to June 2017 with 53 farmers in three districts of Khulna Province, southwest Bangladesh. The surveyed farms were categorized into small, medium and large scale based on the number of culture ponds. The average production, operational costs, gross and net income, net income, and cost-benefit ratios were higher in large farms, followed by medium and small farms.A Cobb-Douglas production function model was used to identify factors influencing shrimp yields, with feed management, health management, pond depth and aeration identified as significant factors. The benefit-cost ratio was higher than 1, indicative of a positive investment efficiency of intensive shrimp farming system for farmers. Major challenges were associated with quality of inputs, high investment, maintenance of biosecurity and disease outbreaks, water quality, limited number of input suppliers and lack of diagnostic services and technical information at farm level. Our findings suggest that there is an urgent need for human capacity development for shrimp farm owners, workers and technicians. It is also important to improve access to quality inputs, rapid and affordable diagnostics and other technical services.

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