Abstract
The study of fish larval nutrition is important as dietary requirements change significantly with growth. Vieja zonata is a cichlid species that is endemic to Mexico. In this study, we investigated the ingestion rate, prey selectivity, and growth of V. zonata larvae that were fed on prey cultured with and without probiotics. We conducted three experiments to test the acceptability of the prey offered, determine the optimal density of the prey items, and observe the effect of probiotics on the larvae's growth. The first experiment tested the acceptability of the prey offered to 5 days post-hatched (dph) V. zonata larvae, and the second experiment determined the optimal density of the prey items. In the third experiment, we individually placed 5 dph larvae (SL = 5.97 ± 0.13 mm; 8.5 ± 0.25 mg) and fed them for 10 days with three different prey items: two rotifer species (Brachionus angularis and Plationus patulus at a density of 20 ind/mL) and a cladoceran species (Moina cf. macrocopa at 1 ind/mL), both cultures with and without probiotics. We counted the prey items consumed daily and provided fresh media with new prey at the above density. We determined the total counts, ingestion rates, and Manly's selectivity index (α(i) ) and measured and weighed the larvae at the beginning and end of the experiment. The endogenous feeding period with the yolk sac lasted until 5 dph, a mixed period with endogenous and exogenous feeding occurred from 5 to 7 dph, and an exogenous feeding period in which they fed on zooplankton was observed from day 7 to 15 dph. Brachionus angularis and Plationus patulus were accepted as prey after 5 dph, and Moina cf. macrocopa was accepted on 11 dph. During the first days of feeding, the preferred prey item was P. patulus, which later switched to M. cf. macrocopa on day 11. We found that the use of prey produced with NanoCrusta probiotics resulted in a significant increase in the somatic growth and weight of V. zonata. Our findings suggest that probiotics may potentially enhance the nutritional value of prey items and promote the growth of V. zonata larvae.