[turtlez]

Hello,

I have these 2 Geo Tapajos Red heads (I think?). Large one is over 4 inches, small one is just about, close to 4 inches. They clearly have different colors, different tail shapes, patterns etc. They swim together, they were labeled as the same species in the tank I bought it from a few months ago (5ish months), I just can't tell what sex they are. The larger one burrowed out a hugeass cave under a 1.5 foot piece of slate,, yes, I mean hugeass cave. The smaller one is more timid. Larger one chases it around. I can't tell if this is mating or aggression. Here is a video, I have zoomed into the tails of each one, so be patient and please watch:

sorry for the crummy lighting, I had to take out the actinic blue tube because my camera acts even more stupidly with that color light.

 

[Graeme]

They both look like females to me but it's hard to tell as they still look young.
Tails don't have much to do with sexing some males will have longer streamers. The males have more pronounced fore head and get a bit of a hump.
here is a picture of a young pair for you the male is the larger one in front.