i for one have had a perfectly healthy looking/acting/swimming/eating betta die in no more than 5 hours after administering for treatment of another fish in the tank. seems a bit too coincidental if you ask me.
and in a lab, are they using store bought random fish, or lines that the lab has bred and raised themselves? that would take the randomness out of it using your OWN genetic line as it doesnt affect ALL bettas similarly. some just cant tolerate it. perhaps the lab knows this and uses "falsified" data. im in the field. i know how it can work sometimes with certain studies. so instead of letting people think its 100% safe at recommended dosage and risk losing a fish that could have otherwise been saved by something simple like doing more waterchanges, i give fair warning to folks who are asking about it. someone else says it is ok and their fish reacts badly and dies and then they will think it would have died anyway and it wasnt the meds fault. i learned the hard way and tell everyone to be careful. dont really know what it is about it that some fish dont tolerate (labrynth organ or otherwise), but i know it killed my otherwise healthy fish!
i will continue to tell folks to only use half dose if they have their heart set on using it for whatever reason.
cheers