i have had this 130L fish tank for over a year not had many issues!
i had a problem with Ich about 2 to 3 months ago gave them treatment all been fine.
today i notice small bumps on the mouths of the tetras like white spots but not like the Ich something different and a bit of Finrot.
so I went to my normal pet shop which is now shut.
I got some Anti-Ulcer & Finrot which i used 10ml of as its says 10 per 50L but i didn't want to risk it.
it turned my Water tank Green I thought that's normal as the Ich Med turned it Blue for a little bit, now that's was this morning i went out for the day to come back to two dead Tetras!
i have a look i can see all the guppies are swimming at teh top of the tanks like no Oxy is there but i have a stone which gives them the extra. one of my plecos is going mad swimming to the top for air seems like as well.
anyway, I did a Big water change to see if its the issue done i think about 50 - 70% change that seemed to work for a few Hours they all seem to relax and breath but I can still see the Catfish and plecos are breathing heavy or Fast i should say.
the tank is still bloody green even after so much water change.
I'm not sure what to do and no pet store is open for supplies any ideas ??? what the hell is going on haven't lost a fish in a long time!
Sorry to read about this and hope there have been no more fatalities.
The treatment that you administered sounds suitable, given what you describe. (The other option could be to use something such as eSHa Exit and eSHa 2000, which can be used together.) As you gave a lower dosage of the medication than recommended, I definitely don't think the treatment itself was the cause of death of the two tetras. Something is definitely awry, though, from what you're describing.
What are your water readings for ammonia, nitrite and nitrate? Keep monitoring these, and additionally do water changes of ~50% over the next few days (even if the levels of each of these are optimum). Let us know what the water reading results are for the next few days.
Did you have a power cut or did you use anything in your home that could have got into the tank too such as paint or an aerosol?