Morphological development of larvae and juveniles of Prochilodus argenteus

Abstract

Prochilodus argenteus is an endemic fish species from the São Francisco River basin that is of high economic and environmental importance. The present study aimed to contribute with information to the taxonomic identification of larvae and juveniles of this species. Larvae , obtained from induced spawning of wild animals, were reared in ponds. Individuals were collected daily and classified into larval stages or juvenile phase. Morphological descriptions and morphometric measurements were performed, together with a piece wise linear regression analysis of the body proportions throughout the development process. Individuals in the preflexion stage had a standard length (SL) of 4.48 to 6.64mm, long to moderate body (BH/SL), small to moderate head (HL/SL), and a small to moderate eye (ED/HL). In the flexion stage, the SL varied from 6.60 to 11.00mm, long to moderate body, moderate head, and small to moderate eye. Larvae in the postflexion stage presented SL of 10.54-19.93mm, moderate body, moderate to big head and small eye. The juvenile phase included specimens with a SL of 18.27 to 42.21mm which presented a moderate to high body, big head and small to moderate eye. Regression analysis showed significant moments of change in rate of increase of the body proportions, presenting a change in the growth pattern from allometry to isometry during the early development.

Early development ofProchilodus nigricansSpix & Agassiz 1829 (Characiformes: Prochilodontidae) in captivity

“…Fish pigmentation consists of an interaction of chromatophores that are located in the stratum spongiosum of the dermis and which is structured by external (biotic and abiotic) and internal (cellular, nervous and hormonal) conditions of the animal (Pittman et al, 2013;Vissio et al, 2021). The colour pattern of P. nigricans larvae is similar to that of other described Prochilodus, being vital for the identification and recognition of larvae of this genus (Abdo et al, 2015;Guimarães et al, 2017;Nakatani et al, 2001;Santos, Pedreira, et al, 2016;Santos, Sales, et al, 2016;Souza et al, 2015).…”

“…Features such as terminal and fleshy mouth, convex dorsal profile, intestine in the posterior position to the middle of the body, scarce pigmentation in the early stages, formation of inconspicuous dark transverse bands on the back and the appearance of a macula between the rays of the dorsal fin (visible in postflexion) in P. nigricans are characters common to the early ontogenetic stages of other species of Prochilodus such as P. argenteus (Guimarães et al, 2017), P. brevis (Nakatani et al, 2001), P. costatus (Santos, Sales, et al, 2016), P. harttii (Abdo et al, 2015), P. lineatus (Nakatani et al, 2001) and P. vimboides (Souza et al, 2015).…”

“…The pattern of ray appearance sequence and complete formation of fins is common within Prochilodus , following the order: caudal, dorsal, anal, pelvic and pectoral (Abdo et al, 2015; Guimarães et al, 2017; Nakatani et al, 2001; Ninhaus‐Silveira et al, 2006; Souza et al, 2015). It is also considered a general pattern of Characiformes (Lima et al, 2021; Oliveira et al, 2022; Santos et al, 2020).…”

Triploidy induction by cold shock in curimba ( Prochilodus argenteus )

“…Therefore, using survival rate as a measure of the triploidy induction success should be taken at the end of the juvenile stage, when all fins are fully formed (Guimarães et al, 2017) and ploidy effect on mortality seems to stabilize.…”