Black Mouth Help

[neon1423]

Hey I could use some help diagnossing a possible problem in my tank.

About the tank first, 30 gallon tall, community fish, years old, undergravel tray as well as an api50 filter.

I have a columbian tetra that looks like someone took a black sharpy and started coloring him black. I also have black skirt tetras, sissortail pasboras, and a congo tetra with very obviously black mouths. Now I dont see any behavioural changes, and I havent had any deaths yet. The tank was beng watched by my roomate while I was away this summer, and I dont think they did any gravel washing. I've been doing 10% water changes daily trying to wash the gravel.

What could be causing the blackness? I called Big Al's and they were stumped, I've even spent a few days doing research online with no results. I know the columbian tetra, black skirt tetra's and the rasboras are very old, almost 3 years old now, but the congo tetras are less then 6 months old.

I've done water tests, ammonium and nitrites were at 0, but nitrates were very high, almost 80.

[Mike L]

 Don't know about the black mouth but if the nitrate has been at that level for long it might be a factor. I would be doing larger water changes. At 10%you are not making enough of a difference to the nitrate level before they will climb again. What do others think. Regards Mike

[neon1423]

so based on advice from another forum, I set up a quarinten tank using 50% water from the tank and 50% new water and isolated all the fish with symptoms. Everyone still seems happy. I just did a water test and the nitrates have come down to about 40. The weird thing is behaviourly everything is normal. Everyone is still eating, swimming, nice fins, everything. it just looks like a toddler took a sharpie to them.

[lucius]

I had this happen to two of my bleeding heart tetras.  It looked like someone coloured in their fins, they are jet black.  I just assumed that they were reaching sexual maturity and left them alone.  I will see if I can get a pic.

[lucius]

Here's a pic of one my bleeding heart tetra's.  As you can see, it looks like someone traced black marker on him (suspect it's a male).  Unfortunately, it's difficult to get a pic of them with the lights on.