The flathead grey mullet, Mugil cephalus , is a native species in Chile with a broad global distribution and recognized importance in aquaculture production in several countries. To evaluate the feasibility of cultivating this species using biofloc technology (BFT), a series of activities and experiments were conducted aiming to acclimate wild-caught individuals to farming conditions and to rear juveniles of different sizes under BFT systems, assessing their growth performance and survival.
Fish were collected at the mouth of the Maipo River (San Antonio, Valparaíso Region) by artisanal fishers and transported to the facilities of PUCV. Juveniles ranging from 2 to 100 g were maintained under controlled conditions, with daily monitoring of water quality parameters. Smaller individuals adapted more readily to formulated feed than larger ones, and no mortalities were observed during acclimation.
An initial trial with juveniles >100 g was performed to evaluate the applicability of BFT for the species. No significant differences in growth were found between fish reared in biofloc and those in water exchange systems, and no mortalities occurred in either treatment. Smaller juveniles were used in subsequent experiments to assess the most suitable carbon source for biofloc formation and the optimal C:N ratio for cultivation. Results indicated that refined sugar yielded better growth and survival outcomes. Chancaca , a traditional unrefined cane sugar commonly used in Chile, was less effective in terms of growth and nutritional composition of the bioflocs . Beet molasses emerged as a viable alternative, showing no significant differences compared to refined sugar. A C:N ratio of 15:1 was recommended, as it resulted in the highest survival rates among the tested ratios (10:1, 15:1, and 20:1).
Overall, findings demonstrate that M. cephalus , even when collected from the wild, can be successfully cultured in biofloc systems. The species exhibited high survival, resilience, and tolerance to water quality fluctuations characteristic of BFT. Further research is encouraged to support the development of M. cephalus as a candidate for the diversification of aquaculture species and systems in Chile, particularly under sustainable farming technologies.