Ty! They are beautiful it would be nice to keep them alive....Tbh I used 2 bottles of Fritz in my 13.5g, granted that was for my fishless cycle though. If I were you I think I'd start with the capful/10g 1x per day since the fish are in. Though I don't think adding more than that would do much harm, just better to err on the side of caution IMO.
Btw, love your clowns too!