Growth performance of thai pangus (Pangasius hypophthalmus) in polyculture system using different supplementary feeds

Fish Diversity in Relation to Salinity Gradient in the Meghna River Estuary, Bangladesh

Variation in salinity is one of the major environmental factors influencing the species diversity of fish in an estuary. Therefore, evaluating the relationship between salinity and species diversity is important. In this study, fish diversity was assessed by fish sampling and visiting local fish markets from February to November 2021. Mean salinity was 10.59 psu (Practical Salinity Unit) and 0.46 psu during the dry and wet seasons, respectively. Harpadon nehereus, Odontamblyopus rubicundus and Pseudapocryptes elongatus species were found as polyhaline (0.06~18.1 psu) species. Anguilla japonica and Arius gagora were abundant in brackish water conditions (0.35~14.2 psu). However, Acanthopagrus latus and Setipinna phasa were found in freshwater conditions (0.06~0.11 psu). The suitability index indicates that commercially important fish species such as Liza parsia, Macrobrachium rosenbergii, Mugil cephalus, Penaeus monodon and Scylla serrata can be used for mariculture during the dry season, and Acanthopagrus latus, Pethia canius and Setipinna phasa during the wet season. Overall, these findings suggest that salinity, water temperature, and chlorophyll-a had a significant (p < 0.05) effect on the fish distribution and assemblage composition in the study area. This finding will be helpful in developing policies for the conservation and management of the aquatic resources in the coastal zone to enrich the blue economy.

The Feasibility of Monoculture and Polyculture of Striped Catfish and Nile Tilapia in Different Proportions and Their Effects on Growth Performance, Productivity, and Financial Revenue

Cultivation of species of high growth rates is a key achievement of sustainable aquaculture development, with the aim of increasing animal protein per capita, maintaining food security and preserving freshwater usage. The present study was conducted to evaluate the feasibility of monoculture and polyculture of striped catfish, Pangasianodon hypophthalmus, and Nile tilapia, Oreochromis niloticus, in different proportions and their effect on growth performance, survival, productivity, feed utilization, body composition, and financial revenue. Five experimental treatments were designed as follows: monoculture of striped catfish (100%), Nile tilapia (100%) and polyculture in different proportions of striped catfish and Nile tilapia (25%:75%; 50%:50%; 75%:25%, respectively), each in three replicates. The fish feeding regime consisted of isonitrogenous (307.80 g kg−1) and isocaloric (19.27 kJ g−1) diets for 14 weeks. The results revealed that the highest growth performance, feed utilization, survival of striped catfish were obtained in monoculture, followed by polyculture of striped catfish and Nile tilapia (in low proportions) (75%:25%). The total production per m3 reached 5.41 kg m−3 in the monoculture of striped catfish, this production decreased in polyculture by 52%, 46% and 23% with 25%; 50%; 75% of striped catfish. The gross margin significantly increased, in case of striped catfish farmed in monoculture, compared to other polyculture proportions. While the gross margin per m−3 of water was 6, 0.5, 1 and 3 $ in monoculture and different polyculture proportions, respectively. Moreover, the feed cost per kilogram of protein gain significantly decreased in the monoculture of striped catfish compared to other polyculture treatments. The growth performance and survival of tilapia showed no significant difference among different treatments. In addition, the proximate chemical composition did not differ in respect to species in different studied treatments. Monoculture of striped catfish is recommended to achieve high production and improve financial revenue per water unit (m−3), for better sustainable development of aquaculture.