Guam

This species is not traded for aquaria but is occasionally exported as bycatch among shipments of other species. It differs from congeners in that the outermost row of teeth are not enlarged plus the interorbital space and cheek below eye are not scaled. Butis spp. are largely nocturnal ambush predators with cryptic...

This species is rare in the aquarium trade and normally expensive when available. It's one of the most easily-identifiable in the genus by the combination of usually 14 pectoral-fin rays, 10 segmented second dorsal-fin rays, relatively small adult size, unique colouration in males and the shape of the first dorsal-fin in males in which the fourth and fifth spines are...

Wild swordtails are a fairly basic green colur. However the vast majority of swordtails available in the hobby today are hybrids of X.helleri with X.maculatus or X.variatus. There are a huge number of selectively-bred varieties available, including wagtail, lyretail, tuxedo, albino, neon, red, green and hi-fin. Swordtails may undergo what appears to be a change in sex. In young fish this may simply be late development. However some adult females develop male characteristics which is thought ...