Both egg and larvae are different between freshwater and marine fish species. Freshwater fish species have generally larger and fewer eggs than marine species. Most freshwater fish species have demersal eggs that develop stuck to various substrata, such as plants or gravels, while eggs of most marine fish species develop in the water column. These differences have consequences for both the evaluation of the quality and the incubation of eggs of freshwater fish species compared with marine species. The larvae of many freshwater fish species are larger and more developed at hatching than their marine counterparts: thus, larval feeding regimes could be different and cannibalism may emerge sooner in certain freshwater fish species. The main differences of egg and larvae between freshwater and marine species are highlighted and the possible implications for aquaculture practices are discussed.