Stress in fish is caused by different factors, particularly the sudden change of salinity at sea during incessant rains, according to Westly Rosario, chief of the Bureau of Fisheries and Aquatic Resources (BFAR)'s National Integrated Fisheries and Technology Development Center. Milkfish or bangus, a cottage industry in Pangasinan, and seabass can tolerate high salinity because of their euryhaline, Rosario said. High ammonia or nitrate levels, low oxygen levels, improper temperature or a high or low pH can cause stress in fish. Heavy rains also cause stress in fish, especially when they are trapped and there is change of water salinity or the water is silty, which clogs their gills, he added.

Visperas, E. (2015, July 23). Fish too suffer from stress. Philippine Star, p. B-7.