Fish have been dieing from some gill disease???

Question

i have had a danio a and some sort of tetra die from what i think is some sort of gill disease. after their death and maybe before and i just didnt notice but their gills are red and a little before their anus on their belly they have an opening that looks almost like something had eatten through it and around that it was red too. i was wondering if maybe they could have some parasite too??? i have been doing water changes every week to lower my nitrates which have been high and the pH is 7.0. i have a heater and an air stone and no other problems that i know of. if you have any other questions you can email me at [e-mail].
♥thanks in advance♥

ALSO!!! out of the two remaining danios a little before the anus there is a bump that seems to be gradually getting bigger. this is the same spot that on the other fish looked like it had gotten eaten out. i took everything out of the tank except for a conch shell and a cave for them and cleaned all the gravel...there was a bunch of light sediment(maybe their leftover poop) is this normal??? also i am using life gaurd as the "broad effect" antibiotic. is that ok???

Answer 1

I agree with MM on this one it sounds more like a bacterial infection.

The red gills could also be caused as was mentioned by a higher ammonia level.
My confusion comes from you having a chnch shell in the tank and your PH remaining at 7. that is odd. If your last two fish are suffering from the same symptoms, I would treat with an anti bacterial and watch them closley.

Answer 2

Have you tested for ammonia? The gill inflamation could also be caused by that, if so and they died what fish are left in there they would certainly take out the stomach area. Usually the eyes are first but ive known em do the belly first.

AJ

Answer 3

That certainly could be a parasite, but more likely it's a bacterial infection. I would suggest a treatment with a broad spectrum antibiotic such as Maracyn 2 or Maracyn TC

MM