Using red tilapia to control Cryptocaryon irritans infestations

Abstract

Marine cultured fish in tropical and sub-tropical regions often suffer from white spot disease, caused by Cryptocaryon irritans infection. This can lead to mass mortality and economic loss. This study investigated the use of seawater-adapted red tilapias (Oreochromis niloticus × O. mossambicus) as scavengers for cleaning tomonts, to protect susceptible marine fish from C. irritans infection. The sensitivity of red tilapia to C. irritans infection, the effectiveness of red tilapia in consuming tomonts, and the efficacy for protecting the vulnerable Trachinotus ovatus from C. irritans infection were evaluated. The results showed that the susceptibility of red tilapia to C. irritans infection was significantly lower than T. ovatus and the rate of tomonts consumption by red tilapia was positively correlated with the number of tomonts in the seawater. The relative percent survival of T. ovatus infected with C. irritans and co-cultured with red tilapias (at a density of 19 red tilapias/m2) was 97.78% at the12 days post-infection. This study indicates that polyculture with red tilapia could be a potential alternative biocontrol strategy to eliminate tomonts, for controlling C. irritans reinfection.