Cichlid
It is exactly what I explained in history: If someone removes a sentence, that person also has to deal with associated refereces. People can't just remove a sentence and leave the reference, as it does not directly support the claim it now is associated with. First what the cichlid article said initially, then what it said after the removal (the part in green is what the 1st reference directly supports; the part in red is what the 2nd reference directly supports):

 The actual number of species is therefore unclear, with estimates varying between 1300 and 3000 species, and one source suggesting 1900 species.

 The actual number of species is therefore unclear, with estimates varying between 1300 and 3000 species,.
[ref's:]

Disregarding the minor problem of the people removing the sentence missing the "comma, full stop" issue in the end of this section, it is obviously very problematic to have a refence associated with a sentence it doesn't directly support. This is even more problematic in an article that has had as many problems as this has, where an IP for a long period (years, literally) continuously changed the number of estimated species while absolutely unwilling to provide a reference in support of the various claims (this has been discussed numerous times, e.g. here, here, elsewhere on talk of cichlid, and on talk of WP:AQF). Finally, after several bans and protections of the article, a number was agreed upon and a reference supporting it was located (Stiassny et al, 2007 - first of the two ref's in the above). So, if any sentence in this article needs exact referencing, this would be it. With my 2nd revert and edit summary I assumed later editors would notice the problem and deal with it. Regardless, now I've dealt with it. 212.10.78.109