dwarfgourami
Fish Connoisseur
So sorry to hear about your angels. But you won't give up, will you? It would be such a shame.
It looks like one of two things: either some kind of finrot, or else your tetras have been sneaking out at night to do their evil deed. Either seems quite possible.
What you need to do is rehome your tetras before you get replacement angels (you will, won't you? promise?). And then get yourself a comprehensive test kit. Here in the uk you can get them for 16.99 and they test all the essentials (ammonia, nitrites, nitrates). It's quite easy, you pour a little tank water into a test tube and add a set number of drops of reagent, then wait for it to go a pretty colour to be compared to a colour chart. There's enough here for hundreds of tests so you can make that a routine part of maintenance. So that will save you the trek down to the lfs and you will get more accurate information.
It looks like one of two things: either some kind of finrot, or else your tetras have been sneaking out at night to do their evil deed. Either seems quite possible.
What you need to do is rehome your tetras before you get replacement angels (you will, won't you? promise?). And then get yourself a comprehensive test kit. Here in the uk you can get them for 16.99 and they test all the essentials (ammonia, nitrites, nitrates). It's quite easy, you pour a little tank water into a test tube and add a set number of drops of reagent, then wait for it to go a pretty colour to be compared to a colour chart. There's enough here for hundreds of tests so you can make that a routine part of maintenance. So that will save you the trek down to the lfs and you will get more accurate information.