Fish ID: hitchhiker

[connorlindeman]

About 4 months ago I found a small fry in one of my plant holding tanks. Must have been an egg that came though and somehow made it.
I was able to capture it when I was framing the tank and moved it into a 10g. I didn't have high hopes for it, but here we are 4 months later and it showed up again.
Any ideas what it could be?
I initially though Siamese algae eater, but the details on the ends of the fins seems to different then any algae eater I've seen. Notice the orange and black coloration?

 

[CaptainBarnicles]

I took a screenshot and did a Google image search, closest match I saw was a Bluefin Killifish...what do you think?

 

[GaryE]

It may be Lucania goodei, a common hitchhiker on Florida plants. It's the bluefin killie, though there are different fin colour morphs. It's native to Florida, and it lays its eggs in... plants. I once collected a group together from feeder tanks as I travelled through the northern US - one here, one there, til I had a group.

 

[connorlindeman]

You know that very well could be it. Thanks guys.
The tank it was originally in was full of wild-harvested hornwort from Florida. Pretty cool.

 

[GaryE]

They are shy fish, a little rough on each other, but fine with tankmates. They're often caught with a livebearer - Heterandria formosa, the "least killifish". I caught a red finned one in Orlando. The Lucania shoaled a lot, while the livebearers hid in the weeds.The young of the two species have the same markings and shoal together. I found when I raised the fry of the two species together, they did better than on their own. It was curious - something I have never seen with any other aquarium fish. They weren't closely related, but the similarity was really something.

The black line and what I can see on the fins is what I'd base the identification on. I would say you have a very young male. He'll get pretty.

 

[Colin_T]

baby Madagascan rainbowfish?

 

[JackGulley]

The young of the two species have the same markings and shoal together. I found when I raised the fry of the two species together, they did better than on their own. It was curious - something I have never seen with any other aquarium fish. They weren't closely related, but the similarity was really something.

I’ve heard something similar before about certain species of pygmy cory and otocinclus. Mine didn’t really *school* together, but they have a very similar pattern on their bodies (although the commonly-sold pygmies are greyer than otos) and I’ve heard they will hang out in large numbers in the same areas in a real river.

 

[GaryE]

There is a Corydoras hastatus (a pygmy species) and tetra relationship. The two look almost alike as adults. Unfortunately, I'm drawing a blank on the name of the tetra. Odontichthys kriegi, maybe?

The hastatus are midwater swimmers, and they shoal together nicely. With Lucania and Heterandria, the adults have different niches, but the fry are the shoalers.

It's a great hobby for seeing unexpected things.

 

[connorlindeman]

Four months later and all traces of color on the fins is gone.