My fish have ulcers, raised scales, areas of inflammation
These are usually typical signs of a bacterial infection. Depending on the severity of the problem, the treatment can range from antibacterial bath treatments, to topical treatments or antibiotics. As with virtually all fish disease it is important to make a full examination of both the fish and water to determine if there are any underlying or secondary problems. These must be resolved at the same time as treating the infection.
If, after providing the best possible conditions, there are not clear signs of recovery within 5-7 days, then a revised treatment plan should be introduced. If, for example, a proprietary treatment had been used and there was no improvement, the next stage would be topical treatments combined with an appropriate antibiotic. It is usually advisably to take a swab sample from the lesion (a blood sample would be better because what’s in the blood is a real pathogen) and have this cultured and checked for antibiotic sensitivity so that you know the best treatment. Your local vet should be able to arrange this. Obviously, unless you have some experience and skill, you may need professional help for these procedures. For help with this: koivet.com/help