Ok thanks. I missed that they were blackwater. I do intend to keep the tank fairly soft - tds around 50 and kh around 1; but definitely not blackwater. Do you know why people seem to prefer males ?The main difference as far as hobbyists are concerned would be their physical appearance — coryphaenoides are more elongated IMO and the colors and body markings are different. They are also a blackwater species, much like altum angels or Uaru fernandezyepezi. My experience with them is that they’re a lot more aggressive with each other and with tankmates, where temporalis are usually fairly mild for large fish.