Or not
My H. guttatus are cherry red all of the the time but then they haven't stopped spawning since they arrived...
Actually if they're happy this strain seems to stay bright red. This is a smaller peaceful variety of the notoriously belligerent African jewel, have about a dozen 1/5" juveniles left if anyone would like some (and 80 more at 1/2" - no doubt there will be another batch of eggs within 72 hours of the time the current cohort is removed).