I'm sorry for your loss :(
Hmm.. it looks like it, but the rot that attacks the fins and then the body usually happens over a long period, sometimes months, before it gets to the body.
On the other hand, tetras are notorious for eating fins.. and could of did a number on him and stressed him out to the point he passed away. I only say that, as there isn't rot any where else.. but that isn't always the case.
But you are right, the body looks as if the rot had attacked it, which again, even rot on the body tends to take a bit.
Never seen something like this happen this quickly.. unsure what to say other than you will want to a water change on the tank.
Your plants may not like the salt, most of the time the salt will harm/kill plants.. your tank should be kept closer to 80 all the time - 75 is a bit low for tropical fish.
AQ salt you should not use for more than 10 days, daily water changes will be needed during treatment.
Rot happens if the water quality isn't as good as needed, along with damage to fins - needs damage to form.
How often do you do water changes?
The % of water being changed?
Last edited by Myates; 11-20-2012 at 07:28 PM.