Reproductive biology of the armored catfish Neoplecostomus microps in a coastal Atlantic Forest stream, southeastern Brazil

Abstract

This work aims to analyze reproductive attributes of the species Neoplecostomus microps (Steindachner, 1877), a well-known species of the catfish family Loricariidae but little contemplated in ecological studies. We describe the reproductive behavior of the species and compare the patterns identified in 2 different basins. The specimens (117 males and 102 females), collected in the Macaé River, did not present a bias in sex ratio during the year. In the largest length classes, males predominated and attained earlier maturity than females. The length-weight relationship showed positive allometric growth for both sexes. The variation of the gonadosomatic index and frequency of maturation stages indicated a reproductive period of 4 to 6 mo, starting in September and reaching a peak in November. The mean absolute fecundity was 43.83 (SD = 7.62) oocytes, ranging from 32 to 55 oocytes. The frequency distribution of oocyte diameter of mature ovaries revealed 3 clutches, suggesting batch spawning. A prolonged reproductive period, low fecundity, large eggs, possible parental care, and repeated spawns recorded for N. microps suggest a strategy that maximizes parental fitness. The population structure and reproductive characteristics of this species indicate a tendency toward equilibrium. The early maturation in females in the Macaé River population may favor a more rapid replacement of juveniles in the population as a response to the unstable environmental conditions that the population experiences in the rainy season.