Lovely fish! I adore them, and plan calvus for my 37gal.
Calvus are shy eaters and are carnivores, so if you have other fish that are omnivores (and snag anything meaty asap
) the calvus will not get enough to eat. That is probably one of the biggest problems keeping these cool fish. I have to order mine online so I am really having to pinch some pennies before I can get them.