Turbot larvae stages are still characterized by high mortalities and low resistance to environmental challenges. Curcumin (diferuloylmethane), a polyphenol extract from the roots of Curcuma longa have been gaining attention as promoter of growth and robustness in some marine larval fish species. The aim of this study was to understand how growth performance and redox status of turbot postlarvae is modulated by dietary inclusion of curcumin.
Three dietary treatments were tested in triplicates (n = 3): Control group were fed a diet without curcumin supplementation (CTRL) and two treatments were fed a diet with low or high inclusion of curcumin (LOW and HIGH). The experiment was carryout in two phases, first a growth trial, where 30 days after hatching (DAH) turbot were reared for one month under optimal conditions, until 60 DAH and fed one of the three experimental diets. The second phase, the thermal challenge, took place at the end of the growth trial where the seawater temperature was increased by ± 5ºC for 24h (acute expose). Growth performance was assessed along fish development (43, 50 and 60 DAH) and the antioxidant status were analysed at the end of the experiment and after thermal stress.
At 43 DAH fish from LOW diet presented a similar dry weight (DW) to CTRL and HIGH fish, however HIGH fish were smaller than CTRL fish. The postlarvae from LOW showed the best condition factor (K) compared to the fish from CTRL and HIGH. At 50 DAH the dietary treatments had no impact in K and DW, however the fish from LOW treatment present a significant higher length than the CTRL fish. At the end of the experiment, 60 DAH, the LOW fish presented a higher DW and K than the CTRL fish. Regarding the antioxidant capacity, the dietary treatments had no influence in the biomarkers tested. However, the data of antioxidant status after the acute stress are still under analyses.
To conclude, the supplementation of antioxidants such as curcumin can enhance turbot postlarvae growth, as previously observed in Senegalese sole. However, no clear effect was observed of dietary curcumin as promoter of fish antioxidant capacity during the growth phase. There are still some knowledge gaps in understanding the pathways of action of curcumin in fish physiology.
This work is part of MAXIMUS.PT project (ref. 69769) supported by Portugal and the European Union through FEDER, COMPETE 2020 and CRESC Algarve 2020, in the framework of Portugal 2020; and co-financed by the Portuguese Foundation for Science and Technology through projects UIDB/04326/2020, UIDP/04326/2020 and LA/P/0101/2020 to CCMAR.