Did you mean nitrate or nitrite? My nitrIte Nutrafin test shows pink, while my nitrAte test shows more of a purple hue. If its nitrites, you should start an immediate water change in the region of 80% and forget about new fish for now (see below).
How many Kuhlis are in there and when were they added?
How many Glass Catfish are in there? Which species are they, perhaps "Debauwi Catfish" or P. buffei (this species really needs groups of 8+)? When were they added?
In the early days of a tank, its far safer to add new fish after two weeks of perfect daily results i.e. no ammonia or nitrite; upto (but ideally less than) the overall volume (as in taking numbers and size of fish into consideration) of current fish in your tank.