mousey wrote:I have not heard of oxytetracycline-- just plain old tetracycline.
They are different members of the same group (Cyclines), Oxy is one of the oldest members, it is also known as Terramycin and you may want to look under this name. Other important members of the Cycline group are minocycline and doxycycline.
All drugs in the group are similar and generally work with the same types of bacteria, they are wide-spectrum, biased toward gram-neg bacteria. Because of their similarity, it is hard to be certain which one is the best in any particular situation. The general principle, both for fish and humans, is that the newer drugs tend to be stronger (for instance, doxy even deals with anthrax) and the chances of hitting a resistant strand are smaller. The additional factor in the tank is the possible damage to the biofilter: any antibiotic may wipe out your filter bacteria. In this respect, minocycline seems to be relatively safe.
If you believe that you still have BHS going on (and nobody knows this for sure --- even the people who diagnozed it never saw your fish or photos of it) and still see the symptoms (specifically, redness), you should treat with one of the cycline drugs.
I would personally go with Minocycline (sold as Maracyn2), in part because of its relative safety to the biofilter. Tetracycline/Oxytetracycline are -- concurring with the previous poster here -- more dangerous to the biofilter. Since minocycline is wide-spectrum, even if you don't have BHS but another bacterial infection, it may work.
OTOH, if you see no symptoms right now, waiting a few days and watching is probably the best course of action. Besides other reasons, it will give your biofilter a chance to recover from erythromycin.
hth
good luck