He’s in a fully scrapped tank so plenty of rocks and wood for him to hide in and as for lots of small water changes the tank is already on a drip system which is a continuous water change system so water quality shouldn’t be the culprit but will send a sample to be tested so we can surely element thatI feed mine on ghost shrimp and tilapia fry. I know shrimp is relatively high in thiaminase, but it is a natural food of dats. Tilapia maybe low in thiaminase, but come from a completely different continent. What is natural for dats is to get a variety in their diet. And I think live food is important too.
What your dat has may look like HITH, but I am not sure. Dats are not cichlids.
Yes, dats have their own diseases.
I would go careful on the salt. Dats come from freshwater only. I would keep doing lots of small water changes. Is there any driftwood or similar that he can blend in with? Being in the open can stress dats.
as for a varied diet I agree with that but most of the seafood available here is saltwater creatures which tend to be either high in thiamine or too fatty so I can’t think of a better option other than tilapia as a staple with the occasional shrimp/other seafood