Diversification of production systems has been identified as one of the major strategies for the long‐term sustainability of brackishwater aquaculture. On the context of diversification, a 180‐day culture experiment was carried out where four farming systems were tested: monoculture of mud crab, Scylla serrata (T1), polyculture of mud crab, with mullet Mugil cephalus and shrimp Penaeus indicus (T2), polyculture of mud crab with mullet, shrimp and oyster Crassostrea cuttackensis (T3), polyculture of mud crab with mullet, shrimp, oyster along with periphyton net (T4) covering 10% of the water spread area. There was no significant difference in the growth performances of mud crab, shrimp and oyster among the treatment but a significantly higher (p < .05) final average body weight (ABW) of M.cephalus was recorded in T4 (121.19 ± 2.09 g). Production considering only the fed animals (excluding oyster) was significantly (p < .05) higher in T4 (2,115 kg/ha) compared to other treatments. The overall water quality parameters do not vary significantly (p > .05) among the treatment ponds. Although there was no significant difference in total ammonia nitrogen (TAN) and nitrite‐N, highest value was recorded in T2 (56.23 ± 39.47 µg/L and 185.53 ± 110.71 µg/L) and T1 (55.78 ± 32.26 µg/L and 180.83 ± 103.65 µg/L). The results from the current experiment based on water quality and growth of animals showed that there is no negative interaction between the mud crab and other animals stocked in the polyculture pond which indicated that polyculture provides an efficient and sustainable utilization of resources.

Splitting of the genus Penaeus sensu lato into six new genera based on morphological features alone has been controversial in penaeid shrimp taxonomy. Several studies focused on building phylogenetic relations among the genera of Penaeus sensu lato. However, they lack in utilizing full mitochondrial DNA genome of shrimp representing all the six controversial genera. For the first time, the present study targeted the testing of all the six genera of Penaeus sensu lato for phylogenetic relations utilizing complete mitochondrial genome sequence. In addition, the study reports for the first time about the complete mitochondrial DNA genome sequence of Fenneropenaeus indicus, an important candidate species in aquaculture and fisheries, and utilized it for phylogenomics. The maximum likelihood and Bayesian approaches were deployed to generate and comprehend the phylogenetic relationship among the shrimp in the suborder, Dendrobranchiata. The phylogenetic relations established with limited taxon sampling considered in the study pointed to the monophyly of Penaeus sensu lato and suggested collapsing of the new genera to a single genus. Further, trends in mitogenome‐wide estimates of average amino acid identity in the order Decapoda and the genus Penaeus sensu lato supported restoration of the old genus, Penaeus, rather promoting the creation of new genera.

The e¡ect of methyl farnesoate (MF) administration on the vitellogenesis of the penaeoidean shrimp, Sicyonia ingentis, was studied. The short-and long-term treatment e¡ects as well as the e¡ect of two MF injection regimens (0.1 and 1.0 mg MF/injection) were evaluated. The studies were also carried out to understand the pattern of vitellogenesis in eyestalk ablated adult and juvenile shrimps. A combination of endpoints, haemolymph vitellogenin (Vg) levels, gonadosomatic index (GSI) and histology, was used to study the e¡ect of these treatments. The GSI increased in all the MF-treated shrimp compared with the control shrimps. Although haemolymph Vg levels declined over the experimental period in all the treatments, the Vg levels decreased signi¢cantly only in the short-term treatment with 1.0 mg MF. Similarly, haemolymph protein level also declined over the experimental period in all the treatment groups. However, except in the long-term treatment with 0.1 mg MF, all treatments showed a signi¢cant decrease in haemolymph protein level. Conversely, in all eyestalk ablated adults and juveniles, haemolymphVg, total protein and GSI increased over the experimental period, all of which were higher than the concurrent control. The discrepancy in the vitellogenic pattern between MFtreated and eyestalk ablated shrimp was possibly due to the di¡erence in the ovarian phase of the initial control. Although unilateral eyestalk ablation failed to induce vitellogenesis in juveniles, bilateral ablation induced vitellogenesis, which indicates that juveniles are competent to undergo vitellogenesis. Oocyte growth stimulation by methyl farnesoate B C Paran et al.

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