Erythromycin is a specially compounded broad-spectrum antibiotic which has been shown to be effective against a number of pathogenic bacteria associated with ornamental fish diseases. It was developed for complete but gradual dissolution in freshwater. Erythromycin is primarily effective against bacterial infections. Use For: clamped fins, swollen eyes, heavy or rabid breathing, patchy coloration. Change in swimming behavior or corner hiding can also be signs of possible bacterial infection. All suspected bacterial infections should be treated immediately