Sounds like its mainly shellfish that tend to carry thiamine destroying enzymes. Fish fillets such as trout, bass, and cod are good, and not sure about SW fillets..
The main idea is not to over-feed or primarily feed products that are carp-like (goldfish) or shellfish (shrimp).. it can have a negative effect long-term.
Worms have a great amount of nutritional variety.. supplementing them with the other foods you mentioned should be a good varied diet. Just keep in mind not to overfeed with these many fatty and high protein food, it can lead to other long-term health issues like fatty liver disease.
Other types of fish display it in different ways.. I recently had a friend inherit some very large Syndontis eupterus and a large parrot fish, all about 8". They all suffered horribly from lateral line erosion, and pitting craters near the head, but not nearly as bad as seen on Oscars. Tank maintenance consisted of breaking down the 29g tank once a year to hose off the undergravel filter.. no water changes.
You also see this quite often in many types of saltwater fish due to nutritional deficiencies due to it being nearly impossible to re-create some dietary requirements of saltwater fihs.
Not so much a short mineral boost, but a short boost in electrolytes. The sudden influx of dissolved solids in the water will relieve an osmosis system for a short period, but its only a temporary supplement as fish need a variety of solids (nutrients) to osmoregulate properly. Salt has other side effects that offer short term 'tonic' like effects (slime coat stimulation, increase ion exchange resulting in better gill/oxgyen function, etc).. but a high concentration of salt can put alot of 'pressure' on a fish that doesn't usually deal with alot of solids in the water. It's especially less beneficial if the existing aquarium water is nutrient deprived, as it disallows the fish to absorb a variety of nutrients.
Fish that naturally come from water that are high in solids (rift lake, brackish) will benefit from the use of salt, much more so than fish from soft water (amazon).. However, if you think about the fact that 'aquarium salt' does not effect pH - it's because its much less complex and diverse with nutrients and minerals. Even rift lake salts raise the pH, and are specific to each lake, due to the complexity of the minerals those products contain.
IMO, 'Aquarium Salt' is completely worthless except for using it as a treatment for parasites (Ich) and other health issues. I look at similar to antibiotics - If you take them all the time they will become less effective. Save the salt for when you need it.. if you are worried about adding solids to the water because the fish 'thrive' in those environments, use habitat specific buffers (rift lake, brackish) and water changes to replenish nutrients.
Hope that made better sense?