Fishkill in Taal Lake is a predictive phenomenon. It happens every year during the months of January and February. Provincial Environment Specialist Joe Torreja, in an exclusive interview yesterday, said that recent reports on fishkill due to sulfur upwelling or "duong" is an annual occurrence to watch out for. Last year, the same episode happened from January 29 to February 03. Other fishkill incidents that took place in other months were aggravated by animal refuse from hog raiser that proliferate on the tributaries connected to Taal Lake.

Florendo, V. A. (2014, January 30). 'Duong' causes Taal fishkill. Manila Bulletin, p. B-8.