Good idea, though the cost seems a little much.
I use fish as a tool too..by putting minnows in my koi pond to consume the mosquito larvae between the rocks that the koi cant reach.
Cost is minimal compared to the analytical instrumentation that's required. This acts as a screening device to minimize the need for chemical analyses. (The fish agitation trigger the automatic samplers to run the chemical analyses.)
Plus, the monitoring is continuous, not from individual samples to be run.
I have no connection with this product or company.