Hi and welcome to the forum. I'm so sorry to hear of your loss. :( Poor Hades. He put up a good fight.
For the recordl, I don't really recommend Melafix because there is an ingredient in it that, when overdosed, can severely harm a betta's labyrinth organ, which they rely on to breathe air from the surface with. If you use Melafix again, be very careful with the dosage and err on the side of caution if you aren't sure. It can be a good medication, it just needs to be used with caution is all. The same goes for Bettafix and Pimafix.
Always remember that too much medication can be just as harmful as no medication. It's so hard to diagnose fishy illnesses so there's always a huge possibility that the medication we decide to give them is the wrong kind. When in doubt as to a diagnosis, stick to aquarium salt for external problems and epsom salt for internal ones.
If you have any other questions about your other bettas, don't hesitate to ask. :)