Hi,
Blackmoor are the poor eaters in goldfishes. They hav very poor eyesight. They tend to search food at the bottom of the tank manytimes. So my suggestion is to put any telescopic goldies with this blackmoor. When you add any active and good eating fish it will clear all the food before the blackmoor gets its share. So i recommend any slow moving goldfish would be best suited.
Ryukin
Goldfish Book :
http://petgoldfishsecrets.com/