None I plan on moving my dwarf e cat into his 180 soon which will be plumped with my 160 ray tank. I use salt with the rays and have never used it with the e cat.
I see. Depending on the salt concentration, I'd research how long-term salt affects e-cats. (Sorry, probably needless to say.) IDK if they enter or spend much time in brackish waters but then brackish is a large range 1000-10,000+ ppm. Below 1000 ppm it is not normally considered brackish AFAIK but I assume you will be using only a tiny bit of salt.