Ulcers/Velvet

Methylene Blue and Epsom Salt:

Every fish owner should have methylene blue and Epsom salts on hand, as well as some aquarium salt.
I am not a big fan of long medicine exposure, with the exception of colloidal silver which needs 5 days worth of treatment.
Swim Bladder/Constipation
Epsom salt:
Soothes their skin, reduces swelling, helps with the swim bladder so they can dive properly, and expels backed up faeces.
Soak in a bath 10 minutes – 1 teaspoon of Epsom salts dissolved in 1 gallon of water.
Colloidal Silver
A controversial treatment for everything ailing you, and every animal on Earth, is Colloidal Silver.
Coloidal silver treats a host of external and internal problems, although there seems to be little scientific consensus.
It is also used for disinfecting water (even on the Russian space station MIR).
People used to use silver in the days before antibiotics became popular and it has since mostly fallen out of use.
Wikipedia: “Silver and most silver compounds have an oligodynamic effect and are toxic for bacteria, algae, and fungi in vitro. Among the elements that have this effect, silver is the least toxic for humans.[citation needed] The antibacterial action of silver is dependent on the silver ion.[6] The effectiveness of silver compounds as an antiseptic is based on the ability of the biologically active silver ion (Ag+
) to irreversibly damage key enzyme systems in the cell membranes of pathogens.[6] The antibacterial action of silver has long been known to be enhanced by the presence of an electric field. Applying an electric current across silver electrodes enhances antibiotic action at the anode, likely due to the release of silver into the bacterial culture.[51] The antibacterial action of electrodes coated with silver nanostructures is greatly improved in the presence of an electric field.[52]

Silver, used as a topical antiseptic, is incorporated by bacteria it kills. Thus dead bacteria may be the source of silver which may kill additional bacteria.”

De-Worming

I’m happy for the most part to do a deworming with levamisol, although I really need to get metro, as I have had problems with flagellates which I think is from the environment, I live probably 50 yards or less from a stream.

After that I do an external clean up with Aquadene General cure or tetra Fungistop (colloidal silver), this process takes about a week. One day for the dewormer and five for the silver.

High Nitrates/Ammonias

First step, water change, using a tiny bit extra dechlorinator.
Second step if it doesn’t show improvement add 1g of salt for every 2.5gal roughly.
This small amount is enough to combat immediate effects of high nitrates.
If this still does not work and you suspect high ammonia, the fish will need 1 teaspoon of methylene blue in 10 gal of water. (do this outside the tank to protect silicone and plants).

Outside of parasitic/viral/bacterial problems with these 3 steps one can turn around the outcome of some of the saddest looking fish you have seen….looking at some of the local LFS here.

Hexamita (Hole In The Head)

Looks like hole in the head or Hexamita. I would treat it with metronidazole after giving it a methylene blue bath at double strength for 15 minutes to clean up the wound a bit. If there is secondary infection you may also need Kanacyn/Kanamycin.
You also need to look at water quality closely as well as making sure the fish gets a varied diet containing vitamins and minerals.

KH vs GH & Fish Illness

The following is copied from ‘Fishlore.com’.  Shout out to the Poster ‘sirdarksol’.

sirdarksolsirdarksol is offline

The effects of general hardness on the aquarium are related to osmosis. A fish’ cell membranes flush water in either direction to maintain a balanced water:mineral ratio. Each type of fish has a different preferred hardness. For example, the Amazonian fish like very soft water, while the African cichlids prefer harder water. If the water is too far from a fish’ preferred hardness, it begins suffering from osmotic stress, as the water:mineral ratio in the cells is not kept at an ideal level for it.  Most fish don’t have much of a problem with this. I have my tetras in extremely hard water, and they are doing very well (colorful, active). If stacked on top of other problems (incorrect temperature, excessive wastes), osmotic stress can mean the difference between health and illness.  Lowering hardness is not as bad as lowering pH, but it is incredibly difficult to do. Generally, the only way I know of to do it is to mix pure water (RO, distilled, or rain) with tap water when doing water changes. There are, as far as I know, no chemicals that you can add to a tank to remove minerals.