There was a member here who was really on a hunt for a black tigerfish a few years ago.I can't remember his username but he had Ohio as his location and was willing to pay good coin for one.
About 7monthsThose GATFs are killer looking...how long have you had them?
very cool! what size tank are they in/ what do they eat??? the only reason it might be darker I would think is that it is not in fact a gatf[/QUOTE
You got it completely wrong...just because the color is different, that doesn't mean it's a completely different type of fish.
^Agree with exoticfishguy
Lighting, substrate color can significantly impact the color and appearance. Def. just a H. Goliath but a nice looking one for sure.