Posted 30 August 2009 - 07:33 PM
Me and Drew (before he went defunct) and others have had discussions about MRBD coloration. A lot of it has to do with temperature I believe. I have one in my 75g which this time of year is running about 78 degrees. I have to say his black coloration is pretty washed out but he still maintains at least a flush of red on his belly, and when he is happy he does become quite colorful. Also, there seems to be some regional variation in the black pattern. Me and Arnoldi actually compared some in one of his tanks, where he has roughly equal numbers of MRBD from the Rappahannock drainage and from the James drainage. They are easy to tell apart, since the James specimens have much larger, more distinct black spots on the dorsal surface, while the Rappahannock specimens have a less defined peppering of black. The lemon-yellow fins are a breeding characteristic, though we have seen them with yellow fins for most of the summertime, they generally fade within a few weeks.
Also, I believe someone also mentioned that MRBD caught in lower elevation/lower gradient areas tend to be more likely to stay fired up than those used to cold, higher gradient mountain streams. Hopefully someone can chime in on that, I haven't caught them from enough different sites to really make an observation on that.