A male Betta splendens
This is Mortimer (my pet Betta fish!) He is male Veil tail variation; he has extended finnage length and a non-symmetrical, drooping tail, with caudal fin rays that only split once. This beautiful tropical fish displays shades of cobalt, turquoise, violet, cerulean and touches of deep red. In a blue Veil tail, the top layer of skin cells is more concentrated with iridocytes, or iridescent pigment cells, so these cells appear as a vivid, shimmering blue.