So i have had these issues for a while now and im getting pretty frustrated... I think it might be some sort of internal parasite... Symptoms: flashing, twiching, flicking fins and loss of apetite... They eat but not as much or agressively. No sign of external parasites and water condition is good (i had issues earlier with the water) some suggestions on medicine or anything i can do to help.. i have polypterus, oscar, black knife fish, silverdollars and couple siamece algae eaters.