I was out of town and my wife texted me several pictures of one of our new RETF babies and was worried about the thing she saw on it's back/butt. I have not looked at it up close yet, but plan on doing so tonight.
To me the below picture makes it looks like that maybe some of the medium from the fruit fly cup got in his tank and then ended up on his back and has now dried to him. I asked her while i was out of town to give it a soak in some warm dechlorinated water, but she said he would just climb right out of the water as soon as he was put into it.
Any ideas?