Dwarf or just a runt?

This boy was born 1.5 months ago and he's not nearly as large as his half brothers, who are 2 weeks younger than him. I've never had a rat still small at this age in all my litters. I'm not familiar with dwarf genetics but thought I'd ask just in case. Sorry for the crappy pics lol

(also any guesses on the colour? he's got black eyes and was much darker colour when he was a baby, so I thought blue roan but he doesn't have strong ticking)

https://pbs.twimg.com/media/Cb6psJAVAAAtZRi.jpg

https://pbs.twimg.com/media/Cb6ptr3UYAE6zPM.jpg

Well I know very little about genetics, but he sure is cute. He looks like two of mine, that came out of two himis. Would love to know the name of this particular colour as well.

Dwarf is recessive. I feel like you'd know if you picked up dwarf stock because they do not tend to be cheap. Something like $60 a rat is normal for dwarves since they're harder to breed for with their birthing issues. There's a good chance he was a runt. Also the smaller the litter size the bigger the babies you'll have as there are less completing for the same amount of milk. And from the photos he looks mink to me.

Thanks Marissa! It was a large litter but all but him and his sibling were culled about ~2 weeks in, I guess that early period took a toll on him.

And what makes you say mink out of curiosity? I thought mink was a darker colour

I'm not a rat color expert by any means. But I say mink due to the blue-y gray color and the ticking. Out in the sunlight would be better for showing true colors. Mink and all colors can vary in lightness and darkness. Most lines are full of recessive dilute genes that can wash colors out. Markings with lots of white can wash colors out too.

Roan is also a separate gene and not too common with feeder breeders right now. You'd have to buy into the stock. And he just does't look like a blue to me but this could be the light. The color looks a lot like the minks I started with as well. I don't have minks anymore though.

http://www.paperheartrats.com/dwarfvsregular.jpg
(Excellent size comparison of full grown dwarf and full grown standard)

I had a dwarf rat pop up in one of my 2013 litters. You will be able to tell a dwarf from a runt as they age instead of when they are born. The dwarf when full grown is about the size of a rat that is a little over a month old. The color looks like a platinum to me but I would have to know the colors of the parents for a better analysis. (You get platinum with blue x (ruby-eyed) mink)

I had a downunder that came out of feeder stock too, so random things do happen.