Ankle biting

How do I keep my malti-poo from biting at my ankles. I think he is trying to herd me, but it hurts! Yelling at him doesn't seem to help.

by yelling you're giving him attention for it.

When he's around your feet not biting, give him loads of fuss/treats etc. If he bites ignore, no eye contact, no telling off, nothing, once he stops, praise him again.

He could be doing it through stress, fear, excitement or for attention....
In any case shouting will not help.
I recommend you read a good dog training book (Jean Donaldson`s The Culture Clash, or Dog Training for Dummies) and do some positive training with him.
This will help you understand each other and he will learn what you want of him.

How old is he? My puppy did this when he was tiny and I spent many a morning with him attached to the ankle of my pj's... I just used to squeak at him when he did it, then distract him with something else and praise when he let go! He's grown out of it now but at the time I was worried I'd bought a nutter!

Very firmly bend down push them away with the command "off". If they persist, time out in either a crate or out of the room. Not for long tho just a few minutes, as a puppy has the attention span of a gnat. let into the room again, very matter of fact and ignore again for just few minutes. Message will get through eventually but will take time