My latest tropical fish purchase, but what is it?

Last Friday saw me get my wallet out and purchase a fish. My intention was to buy just three Otocinclus, which I did, but on a whim I also bought a singular specimen of something else.

“How much is that Copeina/Copella?” I asked the two sales assistants. They paused. “the Splash tetra?” they asked. “We’ve had it in for ages. They all came in that size. You can have it for a fiver.”

“I’ll take it,” I said.

The Splash tetra in question caught my eye for two reasons, one, it was much bigger than any Splash tetra I’d ever seen, at nearly three inches total length, and two, because it wasn’t a Splash tetra…

I also purchased it because it was in a busy, over stocked, brightly lit tank, with loads of water flow, and I had a calm, quiet, under stocked planted tank that I could put it into, with the intention of giving it a better life, albeit in the absence of its conspecifics.

Up close

I acclimatised the fish and released it. It looked old, mature, with long fins and a stocky body. It lacked an adipose fin (not all characins have them,) and its scales were large, and plate-like. One scale seamed raised under the fish’s gills, and I wondered if it was one raised scale away from developing dropsy.

It hovered near the surface, first in the shadows, before making its way across the tank. It explored with purpose, something that the average tetra doesn’t do, and seamed quite bold and unafraid, especially for a singleton.

I studied the fins. The dorsal fin looked like that of the Splash tetra, Copella arnoldi, but the tail fin definitely didn’t as it wasn’t extended. Did I have an old, female splash tetra? I debated with myself.

The caudal peduncle was thickset, and that’s part of what attracted me to the fish. The caudal, anal, ventral and pectoral fins were all crimson red in colour, red enough to make it a male of whatever it was, surely?

I googled Copeina guttata, the Red spotted tetra, followed by “Copeina guttata male, and Copeina guttata, female. The size was a match, at maximum 7.6cm, along with the thick peduncle, and the black and white marks and shape of the dorsal fin, but the look of the fish’s face, and its marking weren’t.

My fish didn’t have red spots on its flanks, due to old age possibly, I pondered. But it did have red in the fins like the red in the the fins of mature, male Copeina guttata on the internet. My search continued.

I googled Copeina again, this time the whole genus, before googling Copella, a beautiful genus of fish which appeal to lovers of pencilfish and their relatives, in the family Lebiasinidae. No matches there, too slim, too petite. Mine was a Copeina on steroids.

One more search – Pyrrhulina, but again I pictured them as slim and petite. I hit images…

The family Lebiasinidae is full of misidentified fish, and my google search for Pyrrhulina turned up images of Copella, Copeina and Pyrrhulina, with many misidentified, but it did turn up some key features in common with my fish including the black horizontal line that travels from the lip, though the eye, the to the edge of the gill cover. The head shape was a match too, but which one? I continued to scroll.

I clicked on P.brevis, followed by filamentosa, then boom! Pyrrhulina obermulleri. I think the fish I purchased is Pyrrhulina obermulleri, but information is very scarce. It was described in 1926 by Myers, and has a standard length of 6cm according to Fishbase. So I have a match, for now, but confusingly, the more I google it, the more mis-matched images, synonyms and Copeina guttata turn up.

At the time of writing I’m two days into ownership of the fish. The lack of nerves has turned to slightly boisterous behaviour, as its occasionally chasing my Siamese algae eaters. If I can find some more I will of course buy them, so we’ll see. But I have an ID, for now, and fingers crossed that it won’t turn into menace.

If you reckon its anything else, drop me a line!