We still know very little about the mysterious Crystal rainbow tetra. What we do know is that it’s stunning as a stained glass window.
The Crystal rainbow tetra is still something of a mystery to science, but it’s pretty as a stained glass window.
It’s often said that, as humans, we know more about space than we do about the oceans on the planet we inhabit. In reality that’s probably not strictly true; we don’t even know the size of the cosmos, let alone what might exist within it.
But it continues to surprise me how little we know of what’s much closer to the surface, and this bonny little tetra is one creature we know of, but still know very little about.
I look at this fish and think of a stained glass window, but in terms of a common name, Trochilocharax
ornatus caught on as the Crystal rainbow tetra, orange-tailed glass tetra, or the Hummingbird tetra, depending on who you talk to. Beware of researching by that last common name though, as
Characidium fasciatum, the Darter tetra, is also sometimes called the Hummingbird tetra, and it’s a very different fish.
T. ornatus was first bought to the attention of ichthyologists when it was shipped from Peru in 2003 by German importers Aquarium Glaser. It was originally considered to be of the Heterocharax genus, before being described to science by Zarske in 2010. Zarske opened a new genus,
Trichilocharax, and tribe, trochilocharacini, for the Crystal rainbow tetra due to rather individual-looking dentition and some hooked fin rays that relate to no other characin – to this day we know of no closely related tetra.
other than just ‘Peru’, scientists aren’t sure about the distribution. the specimens used by Zarske to describe the species came from an imported group, and while they know the import came from Iquitos, they don’t know where the fish were caught, or from what kind of habitat.
It’s widely believed T. ornatus hails from small blackwater streams with little flow, low conductivity and negligible hardness, and it does well in these kind of conditions in aquaria. there’s some thought that their true distribution lies in the Rio nanay basin, though preferred water conditions would be near identical to those mentioned.
the new tribe is placed in the subfamily stevardiinae, a group of over 300 species of Central and south American tetras with many members that adopt an internal insemination strategy. It’s believed that the Crystal rainbow tetra does that too.
In the tank, this diminutive delicacy (1.7cm maximum) displays stunning colours under fullspectrum lighting, with blues and greens reflected in their bodies, and males displaying beautiful burnt oranges and yellows in their finnage.
sexes are easy to distinguish, with males harbouring longer, more colourful fins, especially the dorsal and pelvic fins, while females develop a slightly more rounded body.