Dastilbe is an extinct genus of prehistoric marine & freshwater ray-finned fish from the Early Cretaceous of Brazil. It was a relative of modern milkfish.
Only one definitive species is known, D. crandalli <small>Jordan, 1910</small> from the Aptian of the Muribeca Formation (Sergipe-Alagoas Basin) and the Crato Formation, where it is an abundant fossil fish. The species D. elongatus <small>Silvas Santos, 1947</small> from the ParnaÃÂba Basin (Codó Formation) is sometimes considered its own species, but is now generally considered synonymous with D. crandalli. Other studies have found extensive morphological variation within D. crandalli, and have suggested that it may represent a species complex. Potential undescribed species are also known from the Maceió Formation of the Alagoas Basin, and at levels of the Muribeca Formation younger than the levels that D. crandalli was found in.
Several other chanid taxa have previously been assigned to Dastilbe or have even been considered conspecific with D. crandalli, but are now considered distinct genera and species. The species D. minor<nowiki/>' <small>Santos, 1975</small> from the Aptian-aged Marizal Formation of Bahia, was assigned to Dastilbe as a nomen nudum, but was revived and reclassified into its own genus (Nanaichthys) in 2012. The species D. moraesi <small>Santos, 1955</small> from the Barremian/Aptian of Minas Gerais, Brazil (Areado Formation) was placed in its own genus, Francischanos, in 2022. D. batai <small>Gayet, 1989</small> from the Aptian/Albian of Equatorial Guinea, and the only species known outside of Brazil, was reclassified into Parachanos in 2007.
Dastilbe could reach a length of , with a maximum length of about . It was probably an anadromous fish, tolerant of hypersalinity and subjected to frequent mass mortality. Larger individuals of this predatory fish fed on small fishes and probably they were also cannibalistic.