Protective effect of Terminalia catappa leaf extracts against Saprolegniosis on angelfish eggs

The Saprolegniosis causes major reduction egg hatching rate by angelfish (Pterophyllum scalare); therefore, we investigated the effectiveness of two Terminalia catappa extracts (27 celcius and 80 celcius) against S. parasitica on fish eggs. Mycelium growth was evaluated in vitro at 0, 2.5, 5.0 and 10 g/L for 96 h, in solid and liquid medium culture. In an in vivo assay, we tested lower concentrations of hot extract (25, 50 and 100 mg/L) to prevent infection by zoospores. The hot aqueous extract was the most effective, and the concentrations of 5 and 10 g/L demonstrated great efficiency in liquid medium. In vivo conditions, 50 and 100 mg/L of hot extract provided more viable eggs, greater percentage of total larvae and lower percentage of infected eggs. Thus, the hot extract should be used instead of the room-temperature extract as a prophylactic measure, to prevent saprolegniosis in P. scalare eggs and improving the hatching rate.

Automated summary

The study found that hot aqueous extract of Terminalia catappa was the most effective in preventing saprolegniosis in angelfish eggs, especially at concentrations of 5 and 10 g/L in liquid medium.