I would not medicate unless you see clear signs of fin rot as opposed to just damage. Next, angels like to have some cover and your tanks lacks it. If you cannot add some more taller live plants, then use fake ones. One thing to consider when discussing diseases and healing is that one of the things which opens a fish to getting infected is stress, fish which are stressed are going to catch things more easily and find it harder to heal when they do.
Sick fish tend to hide which is hard to do if there is no place to do so.
I am not a fan of Melafix. if a fish needs an antibiotic, it usually needs something a lot stronger than Melafix, imo. Also, unless a fish has something that is not contagious, it should be treated in an H tank where it gets medicated. This means less water so less meds are needed. It means no other fish can catch whatever and there is minimal stress as long as fish who need some cover have it. I am a live plant person, but I also saved some of my earlier fake plants to use in H tanks.
There is no magic trick to keeping fish healthy- there are basically three things that matter: water parameters (which includes quality), waterscape= which means tanks size and then all the things we add and to make it an environment which supports the needs of the fish. I am talking about rock, substrate, wood, live plants and even current. The last leg of this three legged stool is food. Quality really matters and this means ingredients. Better will cost more. But in the long run not having sick fish will save you more than the extra you might spend on dietary considerations.
In terms of food it usually means live is best, frozen is next and then commercial foods which have the fewest fillers and the most real food and which meet the nutritional needs of the fish. Fish need a proper diet and it is up to us to know what that means and then to make the effort to feed these things. I have commercial flake and sinking food, but I do not feed just those things by a long shot. I sometimes think that I have a better assortment of foods for my fish than I have for myself. I do not do live, but I do use all the best options after that. When I kept bn, I regularly fed them zucchini, green beans and the occasional blood worm as well as algae wafers and dry sinking veggie foods.
One lest observation when it comes to treating bacteria things. Most bacteria do better in warmer conditions. So when battling these it can also help to lower the water temp to the bottom of the range that is acceptable for the fish. If you have ever had surgery, you must have noticed how cool it is in the operating room
