Goldfish fry are all black at first, and they change colour as they age. Unless you have a moor, your black goldfish will likely not be black as it grows. <Even for black moors, most will turn dark brown (with a yellow/white tummy) as they age. .....>
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.