In the current context of aquaculture growth, the supplementation of fish diets with alternative plant-based ingredients becomes important, particularly due to its positive impact on fish health and welfare. Evaluating this response can be achieved by subjecting marine fish to challenges with pathogenic bacteria and then assessing their mortality.
The main objective of this work was to evaluate the impact of algae biomasses and extracts, on the gilthead seabream (Sparus aurata) and seabass (Dicentrarchus labrax) fish survival after a challenge exposure to a pathogenic bacteria.
Based on fish trials performed at Aquaculture Research Station (EPPO/IPMA), where fish were fed four diets with different inclusion of micro- and macro-algae extracts (BLEND1, BLEND2, and BLEND3) and a commercial control diet (Winfast, SPAROS Lda.), according to the plan:
1) 33-35 days after hatching (DAH) post-larvae, were fed the respective experimental diets for 1 week before switching to a control feed for a second week, and returning to the functional feeds for another week.
2) 57-58DAH all fish groups were fed a boost diet for 1 week (BLEND6). BLEND2 was eliminated to give place to a CTRL group that did not receive a boost diet.
3) After, fish were subjected to a stress event (air exposure) and to a challenge test, with a pathogenic bacteria, Photobacterium damselae subsp. piscicida.
At the end of the challenge tests, the fish fed with diets containing micro- and macro-algae showed no differences in mortality. Although not significant, a tendency for higher survival was observed in the fish fed with the diets containing microalgae extracts. These results suggest that in the early stages, the performance of fish might benefit from the incorporation of micro- and macro-algae in the diets.
Acknowledgements
This study was funded by PACTO DE INOVAÇÃO BIOECONOMIA AZUL (Project No. C644915664-00000026), AQUARAS (MAR- 02.01.02-FEAMP-0223) and SAUDE&AQUA (MAR 02.05.01-FEAMP-0009). The technical assistance of EPPO and S2AQUAcoLAB staff was highly appreciated throughout the study.