Fulfilling a secret passion, David Nørholm sets up a species tank for a fish that’s more tail fin than body. Meet the wonderful Montezuma swords.
DAVID NØRHOLM Danish aquarist David is a school teacher by day and creates awesome biotopes by night.
I HAVE A CRUSH. It’s one I’ve kind of kept secret, but I love Mexico. I love Mexican food, Mexican football and the Mexican people. But most of all, I love Mexican fish! And so, it was with excellent fortune that I managed to stumble across some offspring of a wild strain of the Mexican fish Xiphophorus montezumae ‘Rio Tamasopo’.
It was not really my intention to embrace them as a project at the time that I did. Regular PFK readers may recall my hillstream biotope with freshwater gobies, which I was aiming to keep running for much longer, but as I was attending a Danish aquarium exhibition, and meeting the exquisite Montezuma swordtails, I felt compelled bring them home! Changes were hastily made, and I decided to turn my future plans for a Mexican river biotope with livebearers into an immediate reality.
What the xiph?
Xiphophorus is a diverse genus of freshwater fish, and the species within it are known in common parlance as the platies and swordtails. Most of them are recognised for either their vibrant colours and distinctive extensions on the tails of males. Swordtails in particular are famed for the elongated lower lobe on the caudal fin of males, which resembles a sword and gives rise to their common name.
These appealing fish belong to the live-bearing side of the Poeciliidae family, and are close relatives of other popular aquarium species such as guppies and mollies. Xiphophorus species are primarily found in the freshwater rivers, streams, and lakes of Central America, particularly in Mexico, Belize, and Guatemala. At time of writing, Fishbase recognises no fewer than 28 different Xiphophorus species.
The Montezuma swordtail, Xiphophorus montezumae, is native to north-eastern Mexico and can be found in the states of Tamaulipas, northern Veracruz and San Luis Potosí. It is named after the Aztec emperor Montezuma II, given that its native range includes areas historically associated with the Aztec civilization.
While the Montezuma swordtail is not as bold in its colouration as several of the commercially bred swordtails, it’s still a stunning fish in its own right. Colours vary when it comes to different type localities, with my own examples being the Rio Tamasopo type.
The base colours of the males of this type are bluish with a tint of silver, overlaid with various black spots, blotches or
