Hi all,
I'm not sure about Otocinclus, I think it is a combination of factors that lead to them being difficult to acclimatise, but they certainly need good quality water. I'm sure if they were fed with vegetables when in transit, the shop etc they would survive much better. You can actually find it is nearly all the herbivorous (aufwuchs feeders) loricariids (Gold Nuggets (Baryancistrus) etc) that are difficult to acclimatise, not just Otocinclus.
The article (by Joe Gargas) I hadn't seen before, but it is one of the best, and most readable, accounts of applicable water chemistry that I have ever read.
I'd like to think that LFSs in the UK are better at fish care than the examples from the USA he gives. I would have slight reservations about the post in that it is intended for the non-planted tank keeper, and as members of this forum have pointed out the adding 50ppm of NO3 to your tank is very different from 50ppm of NO3 being present from the oxidation of NH3 to NO3.
Personally I like to keep conductivity low for all soft water fish (less than 200microS) and I'm fairly confident that this is the successful recipe for the more difficult soft water fish, against that I think both Clive and Tom have kept tanks with soft water fish successfully where the conductivity has been in excess of 500 microS, so something other than a pure osmotic effect is going on.
cheers Darrel