The middle section of the lake basin of the Doce River in Minas Gerais State, Brazil is plagued by grave environmental problems, including the introduction of non-native fish, which reduces the biodiversity of this region. This study reports the presence of two newly-detected non-native species in the Doce River Basin. Sampling efforts included gill nets with mesh size of 3 to 12 mm (measured diagonally) and trawling nets, both of which were used in independent field campaigns in 2002 and 2011. The two new invasive Perciform fishes, Plagioscion squamosissimus (Heckel 1840) and Parachromis managuensis (Günther 1867) were collected in Caratinga and Rio Doce municipalities. These records and other reports on non-native fishes suggest favorable environmental conditions for the establishment of invasive species in this drainage. These invasive species have behavior and diet observed in other wide distribution exotic fish of Rio Doce Basin representing a threat to the 77 native fishes of this region, 37 of which are endangered.

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The Area of Environmental Protection of the Pandeiros River is the largest unit for sustainable use in Minas Gerais state, Brazil. The Pandeiros Wetland in the lower part of this river is considered a nursery for most migratory fish species of the São Francisco River and it is currently threatened by the introduced peacock-bass Cichla piquiti (Kullander & Ferreira, 2006). In this study, a list of fish species from the Pandeiros River was developed and compared with data for populations from other regions in the São Francisco basin. The presence of a new species record for the São Francisco River basin in the Pandeiros, and the particular local biotic and abiotic conditions of that river, support its recognition as an important conservation unit within the basin.

The W chromosome of Megaleporinus trifasciatus was isolated in order to analyze its behavior in the karyotype of this and other species of the family, including forms with differentiated and undifferentiated sex chromosomes. The chromosome was microdissected, and the WMt probe was prepared for the chromosome painting procedure. M. trifasciatus was also cross-hybridized (cross-FISH) using existing probes available for M. macrocephalus (WMm) and M. elongatus (WMe). Two Leporinus species and Semaprochilodus taeniurus, representing a clade close to the Anostomidae, were also cross-hybridized with the objective to better understand the evolution of the sex chromosomes. In the metaphase of female M. trifasciatus, the WMt probe highlighted the whole long arm of the W chromosome and a small, distal portion of the long arm of the Z chromosome. In males, the probe highlighted the distal portion of the long arm of the Z chromosomes. The hybridization of female M. trifasciatus with the WMe and WMm probes revealed a pattern similar to that encountered using the WMt probe. The WMt, WMm, and WMe probes revealed broad similarities among the species of the genus Megaleporinus, which has a ZZ/ZW system of sex chromosomes, with only minor alterations becoming apparent when analyzed separately.

The state of Maranhão has a vast coastline that promotes the development of coastal recreational fishery, an activity that has attracted more and more fans in recent years. In this context, the objective of this work was to demonstrate the importance of sport fishing as an auxiliary source in monitoring the diversity of fish on the beaches of the metropolitan region of São Luís, Maranhão, through the monitoring of sport fishing tournaments, held in December 2018 on the beach do Olho d‟água and in July 2019, at Araçagi beach. The captured fish were stored in isothermal boxes containing ice and transported to the laboratory for taxonomic identification. 252 specimens were captured, belonging to 19 species, and distributed in 10 families. The family Sciaenidae was the most representative with 3 species. The predominant species were Conodon nobilis and Genyatremus luteus from the Haemulidae family, which together represented 39% of the specimens captured on the Olho d‟água beach and 24% on the Araçagi beach. The individuals of C. nobilis had an average weight of 29.4 ± 12.7 g and an average length of 12.3 ± 2.0 cm, with a curve of weight x length ratio represented by the equation PT = 0.034 CT2.6637 and R2 = 0, 67, with b = 2.67. While in G. luteus, the individuals had an average weight of 96.5 ± 82.2 g and an average length of 15.8 ± 4.4 cm, with a curve of the weight x length ratio represented by the equation: PT = 0.0145CT3.0999 and R2 = 0.81, with b = 3.09. The diversity of fish in beach fisheries can contribute to studies of fishery biology to support the development of management strategies and conservation of fish stocks.