For the past two months or so, my Jewel cichlid of the genus Hemichromis had a chronic ulcer on above his gill plate. The ulcer was around 1 cm in diameter and was progressively getting deeper into the fish's tissue. By the time of the treatment, the ulcer had exposed a small part of the fish's spinal chord. As such, I used a salt dip treatment to try to cure the ulcer. I used a 3-3.5% salt solution (similar to that of marine water) which was made by dissolving roughly 6-7 tablespoons of aquarium salt into a 1/2 gallon container. I then netted the Jewel cichlid out of the tank and placed him into the salt water. I waited for 30 minutes and I monitored the Jewel cichlid's health in the salt solution. After the 30 minutes, I put the Jewel cichlid back into the main fish tank and let him recover.

The main logic behind this treatment is that the ulcer is likely caused by bacteria, possibly of the Aeromonas type. Hopefully the salt will dehydrate the bacteria through osmosis, because the water inside the bacteria will diffuse out of the bacteria's cell membrane and into the salt solution. This will kill the bacteria. The bacteria will die before the fish does because of the bacteria's smaller volume being a prokaryotic cell compared to the eukaryotic cells in the fish.

Update 4/20/2022: The Jewel cichlid has nearly fully recovered from the treatment and is eating well. The ulcer has seen improvement because it has a less red color.

Update 4/24/2022: The Jewel cichlid's ulcer shows improvement as it has stopped growing deeper and has become smaller and less red in color.