This study investigated the effect of intermittent feeding on the water quality, occurrence of skin parasites, feed consumption, and growth performance of juveniles (102.7 ± 5.1 g) longfin yellowtail, Seriola rivoliana. Fish were exposed for 89 days to six different feeding regimes: continuous daily feeding fed one or twice a day (treatment 24R1 and 24R2); 2-day fasting and refed once or twice a day for 1 day (treatment 48R1 and 48R2); and 3-day fasting and refed once or twice a day for 1 day (treatment 96R1 and 96R2). Water quality was not affected by feeding strategies. Likewise, condition factor was not affected by fasting up 48 hr. On the other hand, lowest survival in 96R1 was not related with abundance of skin parasites (Neobenedenia girellae). Specific growth rate, feed intake, feed efficiency, and morphological indices were not statistically different (p > 0.05) between 2 days fasted fish and continuously fed fish. Partial compensatory growth in 48R2 could be attributed to a hyperphagic consumption (8.2 ± 1.1 g day −1 fish −1 ) and feed conversion efficiency (0.61 ± 0.03). A feeding strategy based on cyclical 48 hr of starvation followed by 1 day of refeeding twice may be used for on-growing juvenile longfin yellowtail without reduction in growth or welfare of fish.

A, et al. Lack of compensatory growth response in longfin yellowtail (Seriola rivoliana, Valenciennes, 1833) juveniles related to cyclical fasting and refeeding under rearing conditions.

Some yeast strains have been proposed as probiotics to improve the health of cultured fish. Cobia is a tropical benthopelagic fish species with potential for marine aquaculture; however, one of the main limitations to its large-scale production is the high mortality of fish larvae. In this study, we evaluated the probiotic potential of autochthonous yeasts from the intestines of cobia. Thirty-nine yeast isolates were recovered from the intestinal mucosa of 37 adult healthy cobia by culture methods. Yeasts were identified by sequencing of the ITS and D1/D2 regions of the 28S rRNA gene and typed by RAPD-PCR using the M13 primer. Yeast strains with unique RAPD patterns were characterized in terms of their cell biomass production ability; anti-Vibrio, enzymatic, and hemolytic activity; biofilm production; hydrophobicity; autoaggregation; polyamine production; safety; and protection of cobia larvae against saline stress. Candida haemuloni C27 and Debaryomyces hansenii C10 and C28 were selected as potential probiotics. They did not affect the survival of larvae and showed biomass production >1 g L−1, hydrophobicity >41.47%, hemolytic activity γ, and activity in more than 8 hydrolytic enzymes. The results suggest that the selected yeast strains could be considered as potential probiotic candidates and should be evaluated in cobia larvae.

Note: Values (mean ± SD) in the same row with different superscript letters are significantly different (Tukey's test, p < .05).Abbreviation: S, number of spawn. † Ambient sea water.

RESUMEN.Las malformaciones óseas en peces cultivados representan un gran problema en acuicultura, no sólo por las pérdidas económicas que puede generar el mantenimiento de peces que no serán utilizados, sino también por las complicaciones a nivel fisiológico y morfológico que sufren los peces a lo largo de su ciclo de vida. Estas malformaciones pueden tener inicio desde los primeros estados de desarrollo y estar asociadas a una degeneración de las estructuras óseas con la edad, o a factores genéticos, nutricionales, ambientales, de manejo o una interacción entre éstas, haciéndose difícil la determinación de un solo agente causal. La presente revisión resume la información existente sobre la tipología, momento de aparición y posibles factores causales asociados a las malformaciones esqueléticas con particular énfasis en las malformaciones a nivel craneal.ABSTRACT. Skeletal malformations in farmed fish are a major problem in aquaculture, not only for economic losses that can generate the maintenance of deformed fish, but also by the physiological and morphological implications in fish along life cycle. These malformations may be starting from the earliest stages of development and be associated with a degeneration of the bone structure with age, or genetic, nutritional, environmental factors and management, or relate to each other, making difficult to determine a single causative agent. The present critical review summarizes existing information on type, occurrence and possible causative factors associated with skeletal malformations with particular emphasis on cranial malformations.