This work describes the length-weight relationship (LWR) of 37 fish species from the Taquari River, one of the tributaries of the Jurumirim Reservoir in the high Paranapanema Basin, São Paulo, Brazil. Information was not yet available in FishBase on LWRs of 22 of the fish species and maximum weights (Wt) of 24 of the fish species. New maximum standard lengths are presented for nine species as well as weights for two fish species. † In Memoriam

Knowledge of ichthyoplankton dynamics is extremely important for conservation management as it can provide information about preferential spawning sites, reproductive period, migratory routes and recruitment success, which can be used to guide management and conservation efforts. However, identification of the eggs and larvae of Neotropical freshwater fish is a difficult task. DNA barcodes have emerged as an alternative and highly accurate approach for species identification, but DNA barcoding can be time-consuming and costly. To solve this problem, we aimed to develop a simple protocol based on DNA metabarcoding, to investigate whether it is possible to detect and quantify all species present in a pool of organisms. To do this, 230 larvae were cut in half, one half was sequenced by the Sanger technique and the other half was used to compose six arrays with a pool of larvae that were sequenced using a next-generation technique (NGS). The results of the Sanger sequencing allowed the identification of almost all larvae at species level, and the results from NGS showed high accuracy in species detection, ranging from 83% to 100%, with an average of 95% in all samples. No false positives were detected. The frequency of organisms in the two methods was positively correlated (Pearson), with low variation among species. In conclusion, this protocol represents a considerable advance in ichthyoplankton studies, allowing a rapid, cost-effective, quali-quantitative approach that improves the accuracy of identification.

Neotropical darters of the genus Characidium have a complex systematic history with several examples of sympatry throughout their distribution range in Neotropical freshwaters. Although various species within the genus have been used as models to investigate chromosomal evolution and biogeography, species boundaries and relationships still remain uncertain. Here, we use mitochondrial DNA sequences to perform species delimitation analyses within Characidium and test previous hypotheses of species richness within the Characidium zebra complex and among sympatric morphotypes of C. alipioi. Results indicate high genetic distances within tested species complexes and revealed the presence of strongly supported lineages such as the large C. lauroi group from southeastern Brazil. This suggests that the evolutionary history of these groups may be correlated with biogeographic history. Analyses also reveal that three geographically isolated populations of C. zebra represent a single species, leading us to reject prior hypothesis of multiple species. Species delimitation using mitochondrial data strongly supports the presence of two sympatric species within C. alipioi in southeastern Brazil despite limited morphological variation and conserved chromosomal patterns. These results provide a framework to further the study of systematics and evolution within Characidium.

River damming alters the physical–chemical variables of water and often causes compartmentalisation of aquatic habitats. Seasonality can add complexity to the longitudinal compartmentalisation. The spatial and temporal effects of these two phenomena on the structure of ichthyofauna from a tributary under the influence of damming were evaluated, based on the following hypotheses: (1) transition habitats have the greatest species richness; (2) community similarity decreases with increasing distance between sites; (3) conservation of free‐flowing areas upstream reservoir contributes to the maintenance of migratory species. To evaluate the effects of these two phenomena, twelve monthly fish samples (September/12 to August/13) were performed with gillnets in three sample areas distributed longitudinally in the tributary. Limnological variables were measured in the same sample areas to confirm compartmentalisation. We observed three distinct limnological compartments (lotic, transition and lentic), with increase differentiation during the rainy season. This compartmentalisation influenced fish fauna where localised communities exhibited different compositions among the three sampled habitats. During the rainy season, these differences become pronounced, with transition habitat showing greater species richness than the others. More pronounced differences in species composition and structure in extremes sampling sites were also observed. Migratory fish presented higher proportion of fish composition in lotic habitat. In conclusion, damming and seasonality acted concomitantly as modulators of fish fauna in a tributary influenced by damming. However, compartmentalisation of habitats was the primary driver of ichthyofauna community structure with the rainy season increasing differences in community composition.

Brazil has shown an increase in cage fish farms activity in reservoirs. However, this activity shows potential to cause several changes in the environment with consequences in the structure of native fish fauna community. Thus, the hypothesis of this work is that three cage fish farms, located in the different areas of Chavantes reservoir, high Paraná basin, have potential to interfere with resident fish communities, modifying their structure. Fish were caught in twelve monthly field samplings around three cage fish farms (FF) (FF1 and FF2-Dec/06-Nov/07; FF3-Mar/08-Feb/09) and their respective reference sites (RF) (RF1, RF2 and RF3), using gillnets with 3 to 14 cm between opposite knots. Our data showed that cage fish farms cause increase in fish abundance and biomass around cages. However, Margalef Richness and Shannon-Wiener diversity decreased in these areas. Spatially, fish community around cage fish farms differed from those observed in the reference sites (Permanova two-way: (F = 12.747; p = 0.001)). However, seasonal differences were not observed (F = 1.3732; p = 0.089). This difference was illustrated by NMDS, that showed the formation of two groups, one composed by fish farms and another by reference sites. These differences were mainly influenced by a small group of fish species (Apareiodon affinis, Steindachnerina insculpta (detritivores) and Pimelodus maculatus (generalist) (Simper analysis)) that are able to consume wastes released. We conclude that the cage fish farm act as a driver of alterations in the fish community, increasing the abundance and biomass of a few species which contributes to decrease Richness and Diversity.

This study reports a case of partial albinism in Rhinelepis aspera from the Aguapeí River, Upper Paraná Basin, Brazil and provides a review of albinism cases in freshwater fishes from South America. The captured specimen has depigmentation throughout almost its entire body, with pigmented eyes and little dark spots on the dorsal and caudal fins. It is an adult male, and we suggest that due to the benthic habitat, it would be able to reach adult size, avoiding predators. The review shows a scarcity of this phenomenon in nature.

Dams are considered an important source of modification upon the structure of aquatic communities and their reflexes are diverse on the fish fauna. Although there are several hydroelectric power plants in Brazil, the long-term effects on feeding activity of ichthyofauna are unknown. Thus, this study aimed to investigate the long-term effects of an old reservoir (fifty years) on the trophic dynamics of fish fauna. The diet of 20 fish species was analyzed, identifying 37 food items belonging to six trophic categories, which enable to create six trophic groups. The results found here suggests that throughout the creation of a reservoir, the trophic structure of the fish assemblages tend to reach trophic homeostasis, in which the fish community will be capable of exploring the most available food resources being maintained primarily by the items placed in the categories organic matter and fragments of fish and vegetal.

ABSTRACT. The hybridization is a widely-discussed issue in several studies with fi sh species. For some authors, hybridization may be related with diversifi cation and speciation of several groups, or also with the extinction of populations or species. Diffi culties to diff erentiate species and hybrids may be a problem to correctly apply a management of wild species, because hybrid lineages, especially the advanced ones, may resemble the parental species. The genus Cichla Bloch & Schneider, 1801 constitutes an interesting experimental model, considering that hybridization and taxonomic uncertainties hinder a correct identifi cation. Considering these problems, in this study, we developed genetic methodologies and applied meristic and morphometric approaches in wild samples in order to identify species and for test a possible hybridization between Cichla kelberi Ferreira, 2006 and Cichla piquiti Kullander &Ferreira, 2006. For this, C. kelberi, C. piquiti and potential hybrid (carijó) individuals were collected in Paraná and Tietê rivers (SP, Brazil). For meristic and morphometric methods, the individuals were analyzed using the statistical software Pcord 5:31, while for molecular methods, primers for PCR-multiplex were designed and enzyme for PCR-RFLP were selected, under the species-specifi c nucleotide. All results indicated that the carijó is not an interspecifi c hybrid, because it presented identical genetic pattern and morphology closed to C. piquiti. Thus, we propose that carijó is a C. piquiti morphotype. In addition, this study promotes a new molecular tool that could be used in future research, monitoring and management programs of the genus Cichla.KEYWORDS. Cichla kelberi; Cichla piquiti; carijó; Cluster Similarity; PCA; PCR-multiplex. RESUMO.Abordagens morfológicas e moleculares para delimitação de espécie e investigações de hibridação de duas espécies de Cichla. A hibridação é uma questão amplamente discutida em vários estudos com espécies de peixes. Para alguns autores, hibridações podem estar relacionadas à diversifi cação e especiação de muitos grupos, ou à extinção de populações ou espécies. Difi culdades para diferenciar espécies e híbridos podem ser um problema para aplicar corretamente o manejo de espécies selvagens, porque linhagens híbridas, especialmente as mais avançadas, podem assemelhar-se aos parentais. O gênero Cichla Bloch & Schneider, 1801 constitui um interessante modelo experimental, considerando que a hibridação e as incertezas taxonômicas difi cultam a correta identifi cação. Considerando estes problemas, neste estudo foram desenvolvidas metodologias genéticas e aplicadas abordagens merísticas e morfométricas em amostras selvagens para identifi car espécies e para testar uma possível hibridação entre Cichla kelberi Kullander & Ferreira, 2006 e Cichla piquiti Kullander & Ferreira, 2006. Para isto, C. kelberi, C. piquiti e indivíduos do híbrido em potencial (carijó) foram coletados nos rios Paraná e Tietê (SP, Brasil). Para os métodos merístico e morfométrico, os indivíduos foram...