EMBRYONIC AND PRE-LARVAL DEVELOPMENT AND OTOLITH INCREMENTS IN 2 FILEFISHES, RUDARIUS-ERCODES AND PARAMONACANTHUS-JAPONICUS (MONACANTHIDAE)

Embryonic and pre-larval development, and otolith increments in two mo nacanthid species, Rudarius ercodes and Paramonacanthus japonicus, are described. Eggs of both species were adhesive and nearly spherical in shape, measuring 0.53 mm in diameter. Most of the eggs began to hatch 62 h 39 min after fertilization at 20.7-21.3-degrees-C in R. ercodes and after 29 h at 29.0-29.3-degrees-C in P. japonicus. Newly hatched l arvae, which measured 1.86 and 1.94 mm total length (TL) in R. ercodes and P. japonicus, respectively, had sagittae and lapilli, but lacked asterisci. It was confirmed that one otolith increment formed before h atching in R. ercodes with subsequent increments being formed daily fo r the next two days. However, increments of P. japonicus were so indis tinct as to be uncountable.