Ember Tetras turning black and dying?

[SanityChelle]

So, over the last few weeks, I've lost a few of my male embers in my 30L fighter tank (just the one boy and originally 10 embers). I'm now down to seven, two boys and five girls, with the girls all very fat with eggs.

I've noticed them turning black slowly, from a matter of days to over a week before they die. This was the best picture I could find of it.

Parameters in the tank are Ammonia 0, Nitrite 0, and Nitrates about 10, with the temp at about 28C.

[SanityChelle]

I will also add that the fighter they are in had a really bad wound about a month ago, and I'm still not sure how he did it. This is the before and after furan 2 treatment. He has just gone through a second treatment in the last week (in a medication tank this time) for losing a few scales on his back, which started when he hurt his neck, but hasn't seemed to heal since.

I don't know if this is related, but thought I might add it anyway. The furan 2 from the first treatment couldn't have affected them this way, could it? And still be affecting them now?

[Adrienne]

Ember tetra I would think is going black from internal bleeding which could be bacterial.

I'm surprised your fighter is alive with that amount of damage done to its beard.

[SanityChelle]

So what would you suggest for sorting the bacterial issue?

The fighter's wound got better very quickly after the furan treatment. He was back to flaring and speeding around the tank just a few days after it, and the wound cleared up nicely.

However, I noticed mid last week that the spot on his back had started to grow (see above with only two scales missing, and the larger patch below) so I took him out of the tank to a medi tank this time, as the furan killed off some plants last time and I wanted to avoid that.

He's had four days of furan treatment and is back in the main tank again (he was very lethargic in the medi tank), but still has stress lines as of this morning.

Could both of these wounds on the fighter, and the internal marks on the embers be the same thing? None of the embers have had external injuries, just the blackness.

[Adrienne]

I wouldn't like to guess if it's the same thing or not. If it's internal and a bacteria I would expect furan to help. Same thing with the fighter, if its bacterial I would expect the furan to help.

Yours is about the third post I have seen on the net in nz in the last week about fish showing black. Only conclusive one was a marine which died and an autopsy was done.

[SanityChelle]

Any chance you've got a link to what the autopsy showed? Was it a marine tank you mean?

At the moment, I don't have any embers showing black, so fingers crossed I don't have to do an autopsy.

Since I dosed the entire tank when the fighter had his neck wound, shouldn't that have been enough to stop the bacteria? Is there another bacteria medication that I can easily get, other than furan 2?

[SanityChelle]

Came home and Chuck's wound on his back is twice as big from this morning. There's scales falling off him. I think the embers have been eating his scales, which is why they've been getting sick internally. I'm isolating him in a QT tank once the heater has warmed it up.