So this is new 'news'. The fact the the ammonia 'spiked' - means it wasn't <0.2 ppm or 0.3, Having said that - the 'near the alert level' - would be unlikely to cause this issue - on a short-term basis. The fact that the 'spike' - if there was one - happened when you fed the fish - COULD mean you fed them 'too much'. Though I support the method of adding fish and bacteria on day 1 - there is a point to holding back feeding, etc some for the first couple days. As I believe
@brandon429 would suggest - the likelihood is a possible disease as #1, poor fish quality / stress as #2 and since you mentioned the ammonia spike - #3 would be related to that. But it's doubtful - knowing the research on how much free ammonia clownfish generally tolerate. IF one is going to use the method of bacteria and fish on day 1 - I think it's extremely important to be very frequently measuring. If I had noticed a 'spike' - I would have done an immediate water change (using one of the calculators),