my 20 gallon community has devoloped some type of disease or parasitic infestation. I'm not sure what it was but it killed almost all my fish. Its just a regular 20 gallon community lightly planted and with a 65w cfl. At this point Ive already tried a few types of treatments that the lfs recomended but I don't think Im going to be able to figure it out. So my question is, what do I have to do to make sure my tank is safe again? I did many water changes and recently cleaned it cause I thought it was too dirty but that didnt help. my friend told be to just wait it out and let it runs its course, what should i do? heres what died(in the order they died): 2 bala sharks, 2 tiger barbs,1 blue ram, 1 sailfin pleco,. the survivors so far are a red gourami and 2 bumble bee goby's. All these fish were pretty small and I had them all about 6 months before they started dying and slowly died over the past 3 weeks.