Fifteen (15) fish species were collected from three (3) locations of the Brahmaputra River to determine heavy metals content in fish flesh, and to assess potential human health risk through consumption of those fishes. The contents of heavy metals in aqueous extract of different fish species were determined by an atomic absorption spectrophotometer (AAS) at the Department of Agricultural Chemistry, Bangladesh Agricultural University, during the period from March to June, 2018. The concentrations of Mn, Zn, Cu, Pb, Cd and Cr in different fish species ranged from 41.70-376.62, 38.98-279.08, 3.19-47.91, 2.20-3.73, 0.19-1.20 and 0.59-2.40 mg kg-1, respectively. The study results revealed that the edible portion of fish species of the river contained reasonably higher amount of Mn, Zn, Pb, Cr and Cu compared to some other previous studies carried out elsewhere with freshwater fishes. Among the fish species, mola (Amblypharyngodon mola) showed the highest metal pollution index (20.12) followed by chela (Salmophasia bacaila) (17.72), chanda (Chanda nama) (16.78) and chingri (Macrobrachium sp.) (15.83), while baim (Macrognathus aculeatus) exhibited the lowest (6.79). The calculated daily metal intake for Pb, Mn and Cd for both male and female were higher than that of upper tolerable intake level, which indicates consumption of common fishes of this river, is not safe. Similarly, target hazard quotient (THQ) values for Mn surpassed 5.0 for both male and female, and the same value for Pb also surpassed 5.0 for female indicate that the exposed population are unsafe. The study results also revealed that all individual THQ values of other metals for both male and female surpassed 1, which means exposed population are in level of concern interval. In Bangladesh freshwater river fishes are more popular than farm fishes. However, the study results recommend to aware people about heavy metal contents before consuming fish species of a polluted river system.

An experiment was conducted in the laboratory of the Department of Agricultural Chemistry, Bangladesh Agricultural University (BAU), Mymensingh to determine protein and major mineral nutrients (viz. Ca, Mg, Na, K, P, S and Fe) in different available fish species of the Brahmaputra River of Bangladesh. Total 32 fish samples of 15 fish species were collected from three locations of the river during November 2017. The highest amount of Ca (2.00%), Mg (4.17%), Na (0.41%), K (3.24%), P (0.17%), S (0.129%) and Fe (226.9 mg kg−1) were obtained from chela (Salmophasia bacaila), chanda (Chanda nama), chingri (Macrobrachium sp.), shingi (Heteropneustes fossilis), bele (Glossogobius giuris), baim (Macrognathus aculeatus) and mola (Amblypharyngodon mola), respectively and the sequence of the mineral nutrients was K > Mg > Ca > Na > P > S > Fe. The study results revealed that 100% of daily Ca requirement can be replenished by consuming 100 g fish flesh portion of the chela (Salmophasia bacaila)/ chingri (Macrobrachium sp.)/ bele (Glossogobius giuris). Similarly, among the 15 fish species, 11 and 12 species alone can contribute 100% of Mg and K requirement for human by taking 100 g fish flesh, respectively. The maximum content of N (3.88%) was obtained from shingi (Heteropneustes fossilis), while the minimum (2.81%) was recorded from mola (Amblypharyngodon mola). The protein content among the fish samples varied between 17.6-24.3% with a mean value of 21.2%. Finally, the study results concluded that the common fishes available in the Brahmaputra River are a good source of protein and major mineral nutrients, which contributes in nutrition to the local people of the country.