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Aim In this paper we present a scientometric analysis aimed at to assess and quantify the contribution of Le Cren’s condition factor and the main ideas advanced by ‘Le Cren, 1951’ to studies on the health of individuals or populations in aquatic environments. Specifically, we addressed the following questions: (i) what are the temporal and spatial citation trends of ‘Le Cren, 1951’?; (ii) Which journals cited ‘Le Cren, 1951’ most frequently?; (iii) In which types of aquatic environments and organisms have Le Cren’s condition factor been most commonly applied?; (iv) Which of the main applications addressed in ‘Le Cren, 1951’ have been most frequently used by fisheries scientists?; (v) Which of the methods (i.e., Quételet’s index or body mass index, Fulton’s condition factor, Le Cren’s condition factor, relative weight, residual index and scaled mass index) used to estimate condition factor identified in the papers that cited ‘Le Cren, 1951’ have been most frequently used? In addition, the main criticisms of the use of the relative condition factor are discussed. Methods We carried out a scientometric analysis on the papers published from 1951 to December 2015 that cited Le Cren’s article. The papers were obtained from the Thomson Reuters database (ISI Web of Knowledge, apps.isiknowledge.com) in May 2016. Results In total, 1128 papers were assessed. The number of citations increased significantly over time. Most citations occurred in two journals (Journal of Fish Biology and Journal of Applied Ichthyology). Most of papers were carried out in marine environments. In addition, we show that Le Cren's paper has been cited mainly in articles that estimate the condition factor or the weight-length relationship of populations. Finally, we emphasize that the relative condition factor proposed by Le Cren in 1951 is still the main method used to estimate the body condition of an individual or population. Conclusions Le Cren's significant contribution to animal well-being is undeniable, and we emphasize that among the methods identified in the papers that cited ‘Le Cren, 1951’ that estimated body condition, the relative condition factor proposed by Le Cren in 1951 is still the most commonly used method.

in stream flow discharge, including changes in hydrological processes (with network waterproofing), are common characteristics of human-modified streams, resulting in a decrease in soil percolation and an increase in superficial discharge (Dunne and Leopold 1978). As a consequence, changes in channel stability and morphology and increases in wastewater discharge are expected, which are reflected in ecological aspects, such as changes in species distributions (Maloney and Weller 2010; Alexandre et al. 2010; Cunico et al. 2012), decreases in species richness, and dominance of tolerant species to environmental degradation (Paul and Meyer 2001; Meyer et al. 2005). Although in recent years there has been a significant increase in the studies of the ichthyofauna in tropical streams the knowledge is less extensive than that of temperate areas (Winemiller et al. 2008). In Brazilian inland waters, especially in urban stream, the estimates of the fish diversity are still imprecise due to the lack of complete inventories (Agostinho et al. 2008). First-order streams are abundant and unique components of a river network, they showing high biological diversity and are important for maintenance of the biological integrity of entire ecosystem (Meyer et al. 2007). List of species contributes to build a database on species distribution patterns in altered environments, and to set the ground for future actions of biodiversity management and conservation In the present study, we sampled ichthtyofauna in three first-order streams affected by urban activities, aiming at inventorying the fish species that occur in these particular environments.

The introduction of non-native species is one of the greatest global changes and is a substantial threat to continental fish fauna. This study aimed to evaluate the composition and structure of the fish assemblage of the Azul River, a tributary along the left margin of the Piquiri River basin, to determine the occurrence, abundance and spatial distribution of non-native fish species. Sampling was carried out from February to November 2014 at three sites along the river using of electric fishing equipment. Thirty-two fish species belonging to 20 genera, 11 families and five orders were collected. Eight non-native fish species were recorded, and Gymnotus inaequilabiatus and Oreochromis niloticus were listed among the five most abundant species in the Azul River. The fish fauna followed a distribution pattern expected for the Neotropical region, with a predominance of Characiformes and Siluriformes. However, the high representativeness of the abundance of the non-native species of the Gymnotiformes and Perciformes orders highlights the potential negative impacts on the structure of the fish assemblages of the Azul River due to species introductions.