Application of artificial photoperiod in fish: a factor that increases susceptibility to infectious diseases?

Abstract

This paper describes and evaluates the mortality associated with the potential stressor effect induced by application of artificial photoperiods in rainbow trout (Oncorhynchus mykiss). After application of artificial photoperiods, high mortalities of trout subjected to this management were recorded (36% in LD 14:10 and 25% in LD 24:0) as compared to controls (7%). The recorded signology related to diseased trout included darkening, lethargy and erratic swimming. Among the morphological changes, skin lesions and ulcerative-type necrosis could be observed. Blood tests, histopathology and isolation of pathogens identified as Flavobacterium psychrophilum, associated with Aeromonas, Pseudomonas and Saprolegnia sp., were performed. The application of artificial photoperiods suggests that fish may be more susceptible to opportunistic diseases; thus, it is advisable to emphasize preventive measures in fish subjected to this management.

Mucosal Barrier Functions of Fish under Changing Environmental Conditions

“…Photoperiod manipulation is a practice to regulate sexual maturation and spawning. Though the use of artificial photoperiod has beneficial effects on regulating the reproduction cycles of farmed fish, it has been observed to cause morphological changes, such as skin lesions and ulcerative-type necrosis in rainbow trout, accompanied by mortalities of up to 36% in LD 14:10 and 25% in LD 24:0 compared to the control setup (7%; LD10:14) [62]. Flavobacterium psychrophilum was identified as the causative agent of the mortalities, though the isolation of Aeromonas, Pseudomonas, and Saprolegnia in the diseased fish implies an increased susceptibility of fish to opportunistic diseases.…”

Selenium Nanoparticle-Enriched and Potential Probiotic, Lactiplantibacillus plantarum S14 Strain, a Diet Supplement Beneficial for Rainbow Trout

“…One hundred and two fish were transported to a semi-closed and environmental controlled recirculation system at the Laboratory of Pisciculture and Aquatic Pathology (LPAP), Faculty of Natural and Oceanographical Sciences (Universidad de Concepción). The 102 fish were kept in fiberglass tanks at a density of 25 kg fish m −3 under a 12:12 light:dark photoperiod [ 72 ]. The water quality parameters were monitored and recorded daily during the time fish were maintained at the LPAP (up to 51 days).…”

Aquicultura no século XXI: desenvolvimento econômico, meio ambiente e pesquisas

“…Em ambiente natural existe uma correlação do fotoperíodo com outras variáveis como disponibilidade de alimento, temperatura da água, dinâmica de chuvas. Com isso os peixes desenvolveram uma associação desse fenômeno com diversas reações do organismo, interferindo no desenvolvimento embrionário (VILLAMIZAR et al, 2013), desenvolvimento larval (STUART E DRAWBRIDGE, 2012), crescimento (REYNALTE-TATAJE et al, 2002), maturação sexual (WILKINSON et al, 2010), reprodução (FÁLCON et al, 2010, na resistência a doenças (VALENZUELA et al, 2012), além de outras variáveis fisiológicas.…”

“…Já no tratamento controle, em que foi utilizado o fotoperíodo natural, a mortalidade foi de apenas 7%. Investigando os fatores que levaram a essas diferenças, os pesquisadores verificaram a incidência muito maior de bactérias dos gêneros Aeromonas, Pseudomonas e Flavobacterium nos peixes submetidos aos fotoperíodos artificiais(VALENZUELA et al, 2012).…”