Length‐weight relationships of eleven fish species captured in 18 streams of the Capim River basin, Brazil

Abstract

The length‐weight relationship is important for the study of populational dynamics. This study aimed to describe the length‐weight relationships (LWR) of 11 fish species sampled on 18 streams of the Capim river basin on eastern Amazon. Specimens were captured in 2014, 2015 and 2017, using sieve nets with 2 mm of mesh size. Fixed specimens were fixed in 10% formalin and conserved in alcohol 70%, measured for standard length (SL, 0.1 cm) and total weight (W, 0.01 g). The 11 species analysed were: Hemigrammus bellottii, Hemigrammus ocellifer, Hyphessobrycon heterorhabdus, Iguanodectes rachovii, Copella arnoldi, Nannostomus trifasciatus, Apistogramma regani, Apistogramma agassizii, Gymnorhamphichthys rondoni, Hypopygus lepturus, Anablepsoides urophthalmus.

Length‐weight relationships for seven endemic fish species from streams of the last two large remaining dam‐free tributaries of the Upper Paraná River Floodplain in the Paraná State, Brazil

“…Campos et al, 2020). This effect can be directly associated with the abnormal values of the LWR parameters (Anzueto-Calvo et al, 2017). Although all coefficient of allometry of the species analyzed in this study is within the general range for fishes (2.5 ≥ b ≤ 3.5; Froese, 2006), our LWR estimates were calculated with specimens preserved for more than a year, the older ones collected in the decade of 1990.…”

Reproductive biology of the Amazonian amphibian fish the splash tetra Copella arnoldi with emphasis to histological characterization

“…In a previous study with the same species, Machado et al (2020) got a different result and stated its allometric coefficient was within the general range for any fish species. This difference can resulted from the different methodologies applied in the studies, since Machado et al (2020) only weighted and measured the C. arnoldi exemplars 1 year after their preservation in alcohol, which may cause their retraction by dehydration, once none of the individuals from that study achieved 4 cm length, and in our collection fish ranged from 2 to 5.6 cm. Indeed, in that study the authors suggest future studies to estimate this parameter using fresh and preserved specimens to determine the effects of preservation.…”

Length–weight relationship of eight native fish species from Paraguaçu River basin, Brazil

“…It is important to highlight that our results have a bias because the LWR parameters may have been altered by shrinking and dehydration, promoted by the preservation of the specimens in 4% formalin (Buchheister & Wilson, 2005; Nordeide, 2020). But due to the distance from the sampling sites to the laboratory and the difficulty of measuring in the field, this bias has been unavoidable in the study of stream fish (Campos et al, 2020; Machado et al, 2020; Teixeira da Silva et al, 2021).…”