In this paper (http://eurpub.oxfordjournals.org/content/21/1/43) one can read this:

Results: Blood iron levels were higher in women in the iron fish plus follow-up at 3 months compared with controls, but this was not maintained. At 6 months, haemoglobin and serum iron had fallen in all groups and the proportion of anaemic women had increased.

Conclusions: This study shows that the iron ingot was effective in the short but not longer-term against IDA. Though a novel treatment option, further research is warranted to determine bioavailability of leached iron and whether or not the surface area is large enough for sufficient iron leaching.

Does this mean that the whole thing is another bogus gimmick which only survives because it’s a cute thing which first-worlders like to throw money at, and write articles about?