Zahid survived because he was parking his car outside the mosque with his wife when the shooting began. He saw a body, which he initially thought was someone who had fainted.
Once he realised what was happening, he fled.
Ismail, 36, was father to three young children - Nadiya, 5, Adam, 3, and Yusuf, 1. His mother also depended on him and the shop.
"The responsibility falls on us now," said Zahid. He has temporarily stopped working at another job to keep the dairy going.
A steady stream of customers were dropping into the small, bright blue shop with flowers and to give the family members a hug this morning.
The footpath outside was covered in chalked messages of support from customers: "Your Loss is Our Loss" and "We Are So Sorry".
Cavel Brookland, from Riccarton, said she had driven across town to give her sympathy to the family.
"I've never actually been to the dairy. I've been past it hundreds of times. And when I read one of the victims was from there, I decided I was coming here today no matter what, to pay my respects."
Zahid described his brother Junaid as "the better twin".
"Seriously, he is way more religiously inclined. He is in paradise because of that."
He picked up his twin brother's car from the mosque on Deans Ave yesterday and religious music was blaring from the stereo when he turned it on.
But the family have been unable to pick up Junaid's body. They had wanted to bury him within 24 hours, in line with Muslim custom. It has now been four days since his death.
They have appealed right to the top - to the Prime Minister's office - to get it back.
Zahid said he saw his brother's body in the mosque and had shown a police officer at the site a picture of his brother.