Just wanted to pass along a recent successful treatment of my sick Nothobranchius foerschi.  The symptoms observed were clamping of fins and the fish all huddled in a bottom corner of the tank.  They appeared to be wasting away although only 4 months old.  Thinking the usual disease in nothos is velvet, I gradually added kosher salt up to a dose of 2 tsp/gal for about 3 days.  They appeared to get marginally better; they swam off bottom, but were still looking thin and weak.  Figuring it might be a bacterial disease either primarily or a secondary, I looked on my shelves for a antibiotic I could use.  All I had was SeaChem Sulfaplex which says it is good for protozoan, fungal and bacterial diseases.. so why not.  I treated the same 10 gal tank (bare bottomed with a few plants and sponge filter) with Sulfaplex as per instructions.  This treatment was continued every three days for a total of 3 treatments. I did a 50% water change just before the 2nd and third treatments.  The fish got better after each treatment, but were clearly not totally back to normal until a day of two after the third and final treatment.  Looking great now.  I also did this treatment on Nothobranchius rachovii that were just starting to clamp up; with or without the elevated salt treatment. They also recovered very nicely. I should note that fish did not originally have any added salt when they got sick. This is because my auto-water change system does not accommodate this.  Although some of my nothos have done fine without added salt once they reach 2-3 months of age, prophylactic salt addition seems to be more protective of other notho species. It's been about a month now and these fish seem to have completely recovered.

Hi Keith.  You might want a separate rack for the Nothos.

In my experience, a higher temp helps with clamping, low-80's. It might be your tanks got a little cold.