The silverside Chirostoma estor is an endangered fish species native to the Pátzcuaro’s Lake, located in the Central Part of Mexico. In this study the ossification process of C. estor was evaluated in specimens under culture conditions. Results show that the ossification of the first skeletal structures begin between 30 to 45 days after hatching (dah), and the process concludes between 60 to 100 dah. Therefore, the first two months of life of the species must be closely supervised, since the ossification process is highly susceptible to the influence of biotic, abiotic, and physicochemical factors that may produce skeletal deformities.
For this study, the double staining protocol (Darias et al., 2010) was used. Incubation times and temperatures were adjusted accordingly to fish size and morphological characteristics, to achieve optimal stain of cartilaginous and bony tissues.
Fish were obtained from the hatchery at the Instituto de Investigaciones Forestales y Agropecuarias (IIAF), Universidad Michoacana de San Nicolás de Hidalgo (UMSNH).
Fifteen fish were sampled from the following intervals of age: 10 to 30, 30 to 45, 45 to 60 and 60 to 100 days after hatching (dah). Fish were fed according to the protocol described by Martínez-Palacios et al. (2002). For newly hatched larvae, the photoperiod applied was 24 h light: 0 h dark. For larvae since 10 dah and juveniles, natural photoperiod (12L:12D) was applied.
The total body length for each of the four sampled groups of age was the following: