Abstract
Survey of amoebae was attempted at oscar Asteronotus ocellatus farms in Thailand. In 2002-2003, 120 asymptomatic oscar and 12 samples of rearing water in cultured pond were collected randomly at six different oscar farms and tried to isolate amoebae. Amoebae were isolated from 18 fish (15%) and 3 water samples (25%). Based on the morphological characteristics, they were classified into four different groups (Groups 1-4). Amoeba in Group 1 had two stages distinguished by the presence of the spiny-pseudopodia trophozoite and a double walled polygonal cyst. Group 2 had eruptive trophozoite, biflagella and cyst with smooth and thick wall. Group 3 only formed a typical fan-like trophozoite. Group 4 showed two distinct stages including a trophozoite with numerous tiny subpseudopodia and cyst of various shapes. These amoebae were classified into the four genera, Acanthamoeba, Naegleria, Vannella, and Filamoeba, respectively. The data indicated that Acanthamoeba was dominant in the isolated amoebae. As a result, amoebae in the genera Acanthamoeba, Naegleria, Vannella, and Filamoeba were detected at the rate of 38, 33, 19 and 10%, respectively. In this study, it was demonstrated that some amoebae were living in fish and rearing water.
