Fish Kill
It was a beautiful garden wedding in a resort, with Taal volcano as background. The lake water was inviting but because we were all dressed up in formal attire, we decided to go swimming the following day. No one in the group has tried swimming in Taal lake so the idea sounded exciting.
Our excitement was replaced by frustration when we saw hundreds of small tilapia floating and the foul smell was starting to be unbearable. Fish kill, said the resort owner who has witnessed such happening almost every year since he put up the resort. He owns fish cages, too so he knew more or less why such occurs as explained by Bureau of Fisheries experts in their area. That particular fish kill I witnessed for the first time was caused by toxic gas emissions of hydrogen sulfide (H2S).
This gas is produced through decomposition of organic matters in the lake such as uneaten fish feeds, fish feces and domestic feces that accumulate at the bottom waters. The improper aquaculture practice by local operators in the lake such as intensive feeding and overstocking of tilapia fry in fish cages had caused the fish kill.
While fish kills are natural events, this can be prevented by practicing environmentally sound aquaculture. The natural process that spread the nutrients in the lake cannot be controlled but by following the recommended cage density and feeding practices, the number of nutrients that trigger pollutants in the lake could be reduced.
I appreciated the learnings I got from the BFAR expert through the resort owner. And by the way, hydrogen sulfide is partially responsible for the foul odor of rotten eggs and flatulence. So, now you know the reason why you complain when foul odor lingers in the air.
