My only issue would be the initial impact of inserting that Radio tracking device, I understand its absolutely no harm to the fish physically but owning fish myself i know when they get stressed they tend to hide therefor not giving you the most data possible particularly in 24 hours, Ive seen a GPS system they used here in Sydney harbour to track Bull Shark movements... some interesting stuff...  http://gpscreate.com/case-studies/shark/  You are in the Amazon... i understand that, just food for thought.