Unknown fry in tank

We have 2 glass catfish and two blue tetras in our tank. About a month ago a baby appeared, but only one. It's surviving and thriving but my kids and I are curious: WHAT IS IT? And where did it come from?!? Lol

*sorry the pix aren't better*

I woul say it could be one of your tetras babies.

Agree, it has the appearance of a tetra. Assuming the egg/fry did not happen to come in with a plant or something, you could have a male/female. This species of tetra will readily spawn, and eggs are scattered. Most will be eaten immediately by any fish finding them, including the parents. If an egg should manage to fall in cover where it is not detected--this can be in a wood crevice, in plants, in the filter, etc), it can hatch and the fry can feed off of infusoria and micro foods.

Byron.