I use meth blue mainly as an antifungal, acriflavine as an antibacterial and antiparasite for fish sensitive to copper or malachite, and furan as an antibacterial. Malachite and copper are very effective on fish not sensitive to them. Formadehyde is also good as an antivirul but like the previous two should be used with caution. Many of these treatments such as copper, malachite, quinine can cause temporary sterility in fish so you need to be careful if breeding.