Well my sister gave me loads of stuff for the fish when i started.
And the other month i got loads of new fish and they all started dying.
I did water changes and had the right stuff in the water.
And i noticed i had this velvet medicine.
And i seen that they had similar symptoms, so i started using that and they've been fine ever since.
Its the king british make and it also allows a barrier to stop infection from other things too.
There are loads of illnesses so you could end up spending more on treatments than your entire setup cost not to mention that most treatments have BBE dates.
I've been keeping for years and never needed any. Regular water changes and quarantine new fish (it is worth buying a quarantine tank) is all you need to do. If a fish looks sick either quarantine and then purchase the appropriate treatment or put it out of its misery and move on.
The reason i ask, is because I remember reading on here that someone just stocked 2 meds to treat all common ailments, and I was just wondering what they were.
Unless you are keeping some wild caught fish that have a tendancy to suffer from disease in captivity (ie seahorses), i don't think it is worth having a fully stocked med cabinet. Maybe some Melafix and Primafix, but other than that it isn't really worth it. To cover all diseases you would have tons and tons of meds and most likely will never need any of them. Just qt new fish and keep up w/ water changes and you should be disease free for the most part.