The Monaco shrimp Lysmata seticaudata is a warm temperate species with strong potential for the marine aquarium industry and knowledge on embryo production and brood loss during incubation is essential for the establishment of proper maturation techniques. Average (±SD) brood size of small (total length (TL) 40–44 mm), medium (TL 48–52 mm) and large (TL 58–62 mm) simultaneous hermaphroditic (SH) phase were 753 (±215), 1351 (±163) and 1810 (±264) newly extruded embryos, respectively, in early reproductive season (ERS); and 745 (±258), 1314 (±191) and 1813 (±219), respectively, in late reproductive season (LRS). Senescence does not seem to occur in the Monaco shrimp, since during both ERS and LRS larger SH shrimp always presented a higher number of embryos and negative allometry was not recorded. No significant differences in brood size were recorded among broods at different embryonic stages of shrimp in the same size-class in both ERS and LRS. Brood losses recorded from embryonic Stage 1 to Stage 4 for small, medium and large shrimp were 14.3%, 11.3% and 8.9%, respectively, for ERS and 10.9%, 14.4% and 12.2%, respectively, for LRS. The mean embryo volume in the same development stage was not significantly different among the small, medium and large shrimp, and between ERS and LRS for shrimp of same size-class. For all shrimp size-classes during both ERS and LRS, mean embryo volume significantly increased from 108.5% to 127.9%, from first to last embryonic stage. The occurrence of sex change does not affect egg production since small females in ERS (before the major period of sex change) and LRS (after the major period of sex change) had similar brood sizes.