Red patches on sides on tetras

  1. n

    nieszhw Initiate Member


    First time poster here.

    I've set up a 75g freshwater tank in my office at work. It's been a loooooong while since I've tried my hand at freshwater fish keeping. I used to run saltwater for about 20 years.

    Anyway, my tank has been set up for about a month, and I've got a few tetras (neon and black) and a few rasboras in it. Some driftwood and some live plants. Nothing fancy yet.

    I've been having some issues with keeping my fish alive. I'll have a tank full of healthy fish one day, and then two or three deaths the next. What's odd is that they all act very similarly when they are on the way out. Generally they stop schooling with the rest of their species. They will move to a separate part of the tank, either high or low. And I've noticed they have red splotches on one side of their bodies, right behind their gills. The other side shows no splotches. The gills themselves do not appear affected.

    I've attached a photo of a neon tetra with these characteristics.


    Once they start this behavior, its usually about 12 hours later they will be dead. This happens often.

    I've had my water tested both at a LFS and I bought a test kit myself. All show water parameters normal. (although water seems to be on the hard side)

    Any ideas?

    Thanks in advance,

  2. P

    Peacefantasy Well Known Member Member

  3. OP

    nieszhw Initiate Member