Best Fin Rot Treatment

[55gal]

We have a case of fin rot in our 55 gallon tank. I have tried treating it with Melafix in the past but it did not work. What would be the best treatment for it? Pretty much all of the fish in the tank have it (though we are very understocked because we can't seem to keep fish healthy so we are not getting new ones) and we have been loosing fish.

 

[snazy]

How do you know it's fin rot and not possibly bad water quality like ammonia causing it? Is your tank cycled and what are the current stats exactly?
Melafix is a very mild medication to prevent gram positive antibacterial infections.
Most diseases in tanks are caused by gram negative pathogens so melafix would be the last one on my list to try.
Get a good antibacterial/fin rot medication that is actually an antibiotic, just be careful because depending on the fish types, not all can tolerate all types of meds.

 

[55gal]

The tank is cycled (and has been for years) but the water quality is not great. While I am at college my dad is left in charge of the tank and he slacks on water changes and over feeds. I am going to do frequent water changes and try my best to get my dad keeping up with it when I leave. When I tested the water on sunday the stats were Ammonia 0 or .25 (I have trouble telling), Nitrite 0, and Nitrates were a bit over 80.

In the tank there are angel fish, bleeding heart tetras, cherry barbs, harlequin rasboras, and a BN pleco. We have not bought new fish for months because our fish have been unhealthy for so long.

Do you think clean water will be enough to heal the fins or will I need to do an antibiotic too? If so what products would you recommend?

 

[PrairieSunflower]

I'd definately start with getting the water quality up to perfect... get the ammonia to 0 and get the nitrates bellow 40.