CRYPTOCARYON-IRRITANS (CILIOPHORA) - PHOTOPERIOD AND TRANSMISSION IN MARINE FISH

The behaviour of Cryptocaryon irritans (Ciliophora), isolated from the six-striped grouper, Grammistes sexlineatus, was evaluated under cont rolled conditions using the mullet (Chelon labrosus) as experimental h ost. Trophont emergence from the epidermis of the fish host and excyst ment within the external environment are shown to be influenced by pho toperiod, both these events occurring over the dark cycle. Some eviden ce is provided in support of a photopositive response of the theront. These results are discussed in relation to transmission of C. irritans within the coral reef biotope.