New records of the occurrence of Megaleporinus macrocephalus () (Characiformes, Anostomidae) from the basins of the Itapecuru and Mearim rivers in Maranhão, Northeastern Brazil

The “piaussu”, Megaleporinus macrocephalus is an anostomatid fish species native to the basin of the Paraguay River, in the Pantanal biome of western Brazil. However, this species has now been recorded in a number of other drainages, including those of the upper Paraná, Uruguay, Jacuí, Doce, Mucuri, and Paraíba do Sulrivers. This study presents two new records of the occurrence of M. macrocephalus, in the basins of the Itapecuru and Mearim rivers in the state of Maranhão, in the Brazilian Northeast. The piaussu is a large-bodied fish of commercial interest that is widely raised on fish farms, and its occurrence in the Itapecuru and Mearim rivers is likely the result of individuals escaping from fish tanks when they overflow during the rainy season. Morphological analyses and sequences of the Cytochrome Oxidase Subunit I (COI) gene confirmed the taxonomic identification of the specimens as M. macrocephalus. The COI sequences were 99.66% similar to those of M. macrocephalus deposited in the BOLDSystems database. These records extend the known distribution of M. macrocephalus to the basins of the Itapecuru and Mearim rivers in the Brazilian Northeast, highlighting a new case of introduction of exotic fish species into Brazilian river basins.

Computational study of Richness and Diversity Indices of fish species in rivers and other wetland areas and fish marketplaces under Kurigram District, Banglades

The present study revealed that a total of 101 indigenous species of large fish (28 species) and Small Indigenous fish (73 species) belonging to 63 genera and 31 families were observed and identified while 17 exotic fish species were found under 5 families. Among the indigenous species, the highest number of species were found in family Cyprinidae and Bagridae with a relative diversity of 28.28% and 11.11%. In case of group species richness, highest number 27 fish species were found in catfish group followed by 12 species of carp, 8 species of each barbs and minnows, 6 species of eel fish, 8 species of loaches, 4 species of each prawn, snake-headed or airbreathing fish and glass perches, 3 species of each climbing perches and clupeid, 2 species of each goby fish, knifefish and puffer fish, and rest of the group true perch, leaf fish, halfbeak fish, Needlefish, mullet fish, anchovies and killifish has one species. Of the total species, 47 species were considered as least concerned, 10 species as vulnerable, 11 species as endangered, 11 species as critically endangered, 14 species as nearly threatened and 8 species as data deficient. Considering the seasonal variation for all selected areas simultaneously, Shannon-Weaver diversity (H) index were found ranged from 3.53 (May) to 4.37 (January) where the highest Shannon -Weaver diversity index value 4.37 were found in winter season while 3.01 in Phulkumar, 3.73 in Dudhkumar, 3.87 in Dharla, 3.67 in Tista and 3.79 in Brahmaputra were recorded separately.

Fish Diversity and Its Threatened Status of the Dharla River in Bangladesh

Fish diversity of a riverine ecosystem became reduced due to different manmade and natural calamities. This study investigated the present fish biodiversity status of the Dharla River located (25.8103° N, 89.6487° E) in the northern part of Bangladesh from January to December 2018. In this study, the existing fish biodiversity status of the Dharla River was estimated in terms of diversity indices and threatened status (both global and local). Data was collected from the three sampling sites of the river using different fishing gears and three selected fish markets located in the Kurigram district of Bangladesh. A total of 76 fish species were identified belonging to 8 orders, 26 families and 57 genera. The Cyprinidae was the most dominant family represented by 14 species followed by the Danionidae (13 species), Bagridae (8 species) and few minor families. Apart from the indigenous species, nine exotic fish species were also recorded. The Shannon-Weaver diversity (H), Pielous evenness (e) and Margalef richness (D) indices ranged from 3.00 to 3.71, 0.62 to 0.94 and 3.94 to 7.95, respectively. Out of 76 indigenous species, 28 species (37%) were identified as threatened in Bangladesh, which included critically endangered (4), vulnerable (9) and endangered (15) species. Indiscriminate fishing through poisoning and destructive fishing gears were identified as the major threats to fish biodiversity of the Dharla River. Thus, the river serves as considerable support for threatened indigenous fishes. Therefore, necessary steps are needed to stop destructive fishing, establish permanent fish sanctuaries and proper monitoring for maintaining sustainable biodiversity in the Dharla River.

First record of exotic alligator gar, Atractosteus spatula (Actinopterygii: Lepisosteiformes: Lepisosteidae), from Ganga River system, India: A possible threat to indigenous riverine fish diversity

A new record of an exotic alligator gar, Atractosteus spatula (Lacepède, 1803), from an open wetland of the Ganga River was presented in this paper and discussed along with the environmental parameters. Entry of the exotic fish into the natural system was probably a result of uncontrolled ornamental fish trading. Considering threats of this predatory fish to become invasive and disturb riverine fish diversity, possible ways to avoid such risk have been discussed.

Checklist of endemic (Adrianichthyidae, Gobiidae, Zenarchopteridae) and introduced fish in Lake Poso, Sulawesi, Indonesia

Lake Poso is one of the ancient lakes in the world. This lake is known to have high diversity of endemic fish. Several exotic fish species have been introduced to increase the fisheries production in the lake. However, it is reported that the introduced fish is one of the causes of the threat of the existence of endemic fish in this lake. This study aimed to obtain the latest information on endemic (Adrianichthyidae, Gobiidae, and Zenarchopteridae), and introduced fish in Lake Poso. The research was carried out from May to July 2019 at 17 stations on the coast and rivers of Lake Poso. Fish were collected using a seine net, tray net, and hook and line. The results showed that there were 13 species of fish belonging to eight families and 11 genera. A total of six endemic fish species were still found in this study, namely Adrianichthys oophorus, Oryzias nebulosus, O. nigrimas, O. orthognathus, Mugilogobius sarasinorum, and Nomorhamphus celebensis. Seven species of introduced fish were found, namely Anabas testudineus, Aplocheilus panchax, Channa striata, flowerhorn (Cichlasoma sp.), Melanocromis auratus, Oreochromis niloticus, and Trichopodus trichopterus. Cichlids (flowerhorn, M. auratus, and O. niloticus) have the potential to be invasive due to their adaptability and ease of reproduction in Lake Poso. Conservation of the fish endemic to Lake Poso must be a serious concern for the government, academics, and the community. Ex-situ conservation can be a strategy to conserve the endemic fish of Lake Poso through controlled captivity.

Exotic plus native: findings in an unscheduled fish duoculture

The development of native fish aquaculture represents an important alternative to mitigate ecological displacement generated by exotic fish. The introduction of native fish in polyculture systems with high commercial value fishes has provided a useful strategy for sustainable aquaculture development. The present study aims to provide information on tilapia, as an exotic species, and Dormitator latifrons, as a native species, in a duo culture not programmed as such. Using juveniles of Pacific fat sleeper D. latifrons leftovers from another experiment, we decide to analyze and report the biological feasibility of a duoculture system with this species and Nile tilapia (Oreochromis niloticus). Two hundred fifty organisms of each species were placed for 90 days in a concrete tank with a capacity of 50 m3 to evaluate the compatibility of these species. The biological variables measured were growth, survival, feed conversion rate, and protein efficiency. The findings suggest a good interaction between species, with adequate growths and a survival rate of 98%. No antagonistic behavior was observed during confinement, suggesting the duoculture of these species may represent a good alternative for tropical sustainable aquaculture.

​A Study on Fish Diversity, Marketing and Economics in Fish Markets at Kharagpur, West Bengal, India

Background: There is no previous published record regarding different fish species found in fish markets of Kharagpur town. The place is internationally renowned due to first Institute of Technology of India. Due to largest railway establishment in Kharagpur town, an influx of population is always here from different states. As such their food preference and cultural practice is different. Present survey is relevant to depicts fish preference of the town dwellers and socio-economic status of market associated people. Methods: The study have been conducted from November 2018 to January 2020 thoroughly from 13 fish markets of Kharagpur town, West Bengal, India. Fish specimens collected, identified and preserved. Market related data have been collected from different agents, wholesaler etc. through questionnaire interviews. Result: During the study period it has been observed that 28 freshwater inland fish species; 6 freshwater exotic fish species; 19 marine fish species and 4 crustacean species are available in the Kharagpur town. Some marine molluscs like Loligo sp and Sepia sp are also sold here. There are different peoples, those belong from different districts of West Bengal and involved in fish marketing activities. Therefore, a marketing chain is being established which is interdependent to each other with a socio-economic framework. Some measures have been highlighted towards improvement of infrastructure, hygienic conditions.