You definitely can't carry them on (no more than 2 oz. of liquid through security). I think paulW is right, it might not cost you too much, things are very cheap in Ecuador (at least they were in 1996).
Like rallysman said, it's not worth the risk. Could you stand to see the fish you caught taken away to be euthanized?
A battery operated, buzzing device in a checked bag...Hhmmm, I think you may get back in more like 10 days.
Now that the funny part is over, I'll get on my high horse...
It sounds like you want to smuggle exotics into the country, which is not allowed for all the known reasons and I don't care if it is only one fish let alone breeding quantities.
Your going down there for what purpose?, You know your doing wrong so just don't...If God doesn't want to bother with you He'll just turn you over to Carma and you really don't want that! (God gets you in the next life but Carma puts you thru hell in this one ).
And now I'll jump back down and and wish you a safe journey.
but now that you mentioned its deffinitely not worth the risk, i wish i had time to find an exporter, probably not that expensive, but wont have the time to find one etc
thanks guys, maybe ill just take some pics of fish then, i know were spose to go to some fishery up in the Andes before we leave, i think its just trout up there though