No simple links: Absence of correlation between condition factor and immune status under contrasting environmental...

Understanding whether simple morphometric condition indices reflect immune status is increasingly relevant for fish-health assessment in ecological/conservation studies. We examined the relationships between two condition indices (Fulton's K and Le Cren's K') and immune parameters -leukocyte profiles and bacterial agglutination capacity, summarized using principal components analyses- in three sympatric marine fish species sampled under contrasting environmental conditions, including undisturbed reference sites and sites exposed to anthropogenic disturbance. No significant associations were detected between condition indices and immune condition in any species or environmental context. Our results suggest that morphometric body condition indices do not reliably predict immune status in wild fishes highlighting limitations in their use as integrative indicators of fish health.