Sore

Question
I have had my 36 gallon tank set up for 2 years and is very stable.  My pH is 7.0 and I do weekly water changes.  I have a bio wheel filter with about 13 fish.  I recently bought 2 humphead glassfish that I had special ordered and one of them had a small mark on its body that looked to be caused from a scrape.  However over the next couple of days I noticed the "scrape" getting larger with a bump that seems to have broke the skin.  This breaking of skin seems to look more like a red hole.  The fish is still eating, swimming and acting as if nothing is wrong.  What could it be and how should I deal with it?

Answer
Hi Derek

If the fish arrived with the scrape looking mark, it's very well possible that's what it is/was.  Bacteria could've entered through there, and it might just be a bacterial infection.  Keep an eye on the fish, if it starts to look like it's getting a white film/coating on it, especially around the head area, or white thready looking strings on it, or white patchy areas on the fish, that would be like a disease called columnaris(mouth fungus).  It's also a bacterial disease.  These were most likely brought on by the stress from shipping and the handling of the fish.  Or they could've come from a "poor" environment at their last home.  

I'd start a treatment of a broad spectrum antibiotic, I don't which, you'll have to read the label, but Maracyn I or II should treat bacterial infections/comunaris.  Both are generally gram negative bacterias, gram positive bacterias are rare in fresh water fish.

You could also use some salt to help in the treatment.  That will depend on what else is in the tank.  You sound like you're very familiar with aquariums, so obviously plants and snails/inverts don't fair well with salt.  I'd use regular aquarium salt, usual dosage is 1 tablespoon for every 5 gallons.  And keep up with your water changes as well.  Be sure to remove any carbon from your filter before using any meds.

One last thing to think about, using an antibiotic in your tank will kill off most of your beneficial bacteria, which will probably cause a mini cycle to occur.  I'd recommend using a hospital tank, and QT'ing the sick/injured fish.  But, if it's columnaris, that's pretty contagious to the other fish.  So maybe try treating in a QT tank, and keep an eye on all the fish for signs of disease.  If they start showing signs/symptoms, then you'll need to treat that tank as well.  And, when you go to the store to get the antibiotic, pick up a bottle of PimaFix.  It's kind of a natural antibiotic, helps in treating a lot of gram negative diseases and funguses.  You could use that as a treatment in the main tank as well, in case it is something contagious.  Good stuff to have on hand though.  You could try that instead of the antibiotic, but in  your case he's had it awhile now, so I'd be more comfortable using the antibiotic.  There's another product called MelaFix.  It's for bacterial infections as well, but geared more towards the gram positive ones, and is more useful for a general "well being" of the fish, and good for when you have to handle them.  I usually keep a bottle of both on hand at home all the time.  Definitely think about using a second tank though.  Doesn't need to be anything fancy, just a 10 gallon, a filter, small heater that's it.  When you need to QT a fish, just use either some gravel or some filter media from your established tank to instantly cycle that tank when you add the fish to it.

Good luck with the treatment, and hope that helps.  Any more questions, please ask!!

Christy