In early 2011 there were health concerns about fish pedicures, which made headlines in the 'red top' newspapers. (It was more calmly reported by the BBC here:
http://www.bbc.co.uk/news/health-12595809 ).
All that was really said at that time though was that the Health Protection Agency was to carry out an investigation. The end result of that investigation was actually a report that said that the risks from fish pedicures were 'very low' for most people. (
http://www.nhs.uk/news/2011/10October/Pages/hpa-risk-fish-pedicures.aspx ).
However that didn't get a lot of media coverage and it was the earlier headlines which stuck in many people's minds, putting them off paying to have their feet nibbled.
As you've suggested though, there was probably an element of the 'short-term fad' about it as well. As an analogy, I can rember a period when 'anyone who was anyone' went in for colonic irrigation. These days there seem to be far fewer people who are willing to pay to have a hose pipe stuck up their bum ;-)