I never even heard of cyanide fishing. I guess ignorance is bliss. I'll look that up about ottos too.I am aware that cyanide was used to catch saltwater fish, but also heard that even this wasn’t practiced as it once was. It’s the freshwater fish, specifically otocinclus that I question its use on. Seems questionable to practice this with such small fish. I expect a cast net (throw-net) to be quite sufficient. In fact, it can be very efficient in doing the job of catching lots of fish in a relatively short period of time, with a practiced hand.