red growths on black skirt tetra

Question
QUESTION: 40 gal tank has had the following fish for about 3 years (the tetras maybe 2
years): 6 clown loaches (I know that's too many, but, they're very happy and
healthy); 7 panda corys; 5 black skirt tetras and one golden algae eater. I
scoop out visible waste daily and, although I don't have much gravel on the
bottom, I still vacuum every week; do 25% water changes every 2 weeks;
clean the bio wheel filter every 2 weeks; check chemistry every week:
everything is usually perfect except for the ph, which tends to be a bit low at
which point I add ph up. One of the tetras developed red lumps on and
around his head and mouth area about 2 weeks ago. His eating and behavior
have been consistently good (he remains one of the more aggressive tetras in
the tank and has a good appetite.) If it's bacterial, would it be safe for them
and the other fish in the tank to treat with Maracyn? If so, do I remove the
carbon filter? Thanks for any advice you can give!

ANSWER: Hi Marla:  What is your pH normally?  What is the water temperature?  do you add aquarium salt to your tank?  please let me know...dave

---------- FOLLOW-UP ----------

QUESTION: Hi Dave,

The ph is 6.8 right now, and the temp is 79.5.

Answer
If the fish is not in distress then I would just up the temp to 82 degrees and add aquarium salt.  The combination of the two will probably kill whatever is attacking your fish.  On the other hand if its a wound and not an infection the salt will help to prevent infection... dave