Do fights get cancelled when a fighter comes in UNDER the weight division?

There is no lower limit for a fight in a division.

 

The amateurs have lower limits.

 

there must be a limit where the athletic comission wont allow the fight but no official rule about it

 

This. As long as you come in under the limit your good.

 

No. I suppose if one guy is like 30 pounds lighter though the commission won't allow the bout to take place as it becomes a high risk of injury or even death, but I can't recall that ever happening.

 

Wasn't Henry Armstrong usually weigh very less? I'm not sure, I would have to check them out.

 

Would be weird to have a little guy like Chocolatito challenging Deonty Wilder, knocking him out cold in the first few seconds of the first round and then being proudly proclaimed HW champ of the world!

 

Yep, Armstrong and Robinson both weighed less on some occasions. I think Robinson had a few middleweight fights where he weighed 145 and Armstrong fought Ceferino Garcia for the middleweight belt when neither were anywhere near 160.

 

Thanks Ovids. I have noticed that you are kind of a historian.

 

There we go. That's the bout I was thinking of. Ray Robinson first, second, and third bouts with LaMotta

1943-02-26 145 Jake LaMotta 160¾

1943-02-05 144½ Jake LaMotta 160½

1942-10-02 145 Jake LaMotta 157¾

Ray didn't even hit the welterweight limit, and LaMotta as usual couldn't make the middleweight limit. And here's Armstrong vs Garcia for the middleweight championship.

1940-03-01 142 Ceferino Garcia 153½

Also, Mickey Walker "The Toy Bulldog" has more than a few that look like this:
1931-08-17 167 Jack Gagnon 209
1930-11-28 166¼ KO Christner 202

 

Amateurs have a clause - seen a female bout cancelled on the scales because the weight discrepancy was too great.

 

That would be hilarious.

 

Which i find strange because its normal to see hw who are outweighed by a lot of weight all the time.

 

Well honestly the bigger you are the less it really matters it seems. Like, at a lower weight 6 pounds is a huge difference but at heavyweight 6 pounds means **** all.