Introduction. The production of marine fish larvae depends on the use of live food such as rotifers and Artemia, among others. This increases the difficulty and complexity for fish production. For these reasons, acceptable growth rates cannot be maintained using solely live food due to the low nutrient content (1). Also, acceptable growth rates cannot be maintained using live feeds exclusively due to the low nutrient content and restricted intake of these feeds (1). On the other hand, the use of microdiets in larviculture can improve the nutrition of the larvae especially in terms of amino acids profile and protein quality, therefore, implementing co-feeding is expected improved the nutritional status of the larvae and could facilitate the transition to only microdiets (2). The objective of the present study was to evaluate co-feeding during the early development of totoaba (Totoaba macdonaldi) larvae under culture conditions.
Method. Twelve 100-L fiberglass tanks in a recirculating system were supply at a density of 150 larvae/L. Four feeding treatments were performed (T1, T2, T3 and T4): T1 consisted of using the feeding protocol proposed by (3) and T2 doubled the live feed ration according to this protocol. T3 consisted of co-feeding with rotifer-microdiet from Day Post Hatch (DPH) 4, and T4 was to start co-feeding at DPH 12 with nauplii of Artemia-microdiet (Figure 1). Larvae growth (g and cm) and survival were evaluated and the development of the digestive system.
Results and Discussions. No significant differences (P>0.05) were observed on growth, length, and survival. The best growth (g and cm) and survival results were observed in T1 and T2 compared to T3 and T4 (Table 1), however, regarding the ontogenic development, a better development, larvae quality and conformation of the digestive system was observed in the T3 and T4, therefore, based on these results, we could suggest implementing co-feeding from DPH 12, as an early weaning protocol for totoaba larvae, contributing with a promising strategy for the production of this species.
Conclusions. Based on the results of the present study, totoaba larvae could be fed with a co-feeding (Artemia-microdiet) from DPH 12, having growth rates similar to those reported in previous protocols.
References. 1 Fosse P. J., Mattos D. C., Cardoso L D., Radael, M. C., Filho, João Carlos F. F., and Vidal Júnior M. V. (2018). Duration of co-feeding on the Nishikigoi Cyprinus carpio larvae during weaning from live to inert food in an indoor system. Ciência Rural, 48(4). 2 Nhu V., Dierckens K., Nguyen H., Hoang T., Le T., Tran T., Nys C., and Sorgeloos P. (2010). Effect of early co-feeding and different weaning diets on the performance of cobia (Rachycentron canadum) larvae and juveniles. Aquaculture, 305:52-58. 3 Galaviz, M.A., López, L.M., Garcia-Gasca A., Alvarez-Gonzalez, C.A., True, C.D., y Gisbert, E. (2015). Digestive system development and study of acid and alkaline protease digestive capacities using biochemical and molecular approaches in totoaba (Totoaba macdonaldi) larvae. Fish Physiology and Biochemistry, 41:1117-1130.
Acknowledgments. To the SADER-CONACYT grant no. 247698 and the CONACYT scholarship no. 898093