This work aimed to assess the suitability of a microalgal blend as a dietary ingredient for
feeding juveniles of marine carnivorous and herbivorous teleost, as is the case of Sparus aurata and
Mugil cephalus, respectively, and to isolate microorganisms from different media and characterize
them on the base of their enzymatic activities and their antagonism against important fish pathogens.
Thirty juveniles of each species (70 3.2 g S. aurata mean weight and 47 2.8 g M. cephalus mean
weight) were distributed in four tanks (15 individuals each) corresponding to four independent
dietary treatments (control and microalgae diets designed for each species). Fish were fed their
corresponding diets ad libitum for 108 days. At the end of the trial, fish were weighed, and plasma,
liver, perivisceral fat, and the entire intestines were obtained for the evaluation of growth performance
and metabolic assessment. Furthermore, 117 bacterial strains were isolated in different culture media
from the gastrointestinal tract of S. aurata fed the microalgae blend and further characterized for
their potential use as probiotics in aquaculture. S. aurata fed the microalgae-supplemented diet
(25% dietary inclusion) showed a significant increase in weight gain, specific growth rate, feed
efficiency, hepatosomatic, and intestine length indices. However, growth performance and somatic
indices in M. cephalus were not affected by the experimental diets. Plasma samples from S. aurata fed
the microalgal diet revealed higher levels of glucose and triglycerides and a decrease in cortisol levels.
No significant differences were found in any biochemical parameters among the experimental diets
in M. cephalus. In conclusion, both species demonstrated a favorable adaptation to the nutritional
formulation employed [...]
