Handcuffed and wearing a white prison suit, Tarrant did not speak.
Tarrant is scheduled to appear in court again on April 5.
New Zealand's prime minister Jacinda Arden has vowed to change the country's gun laws in the wake of the shooting spree that stunned the world.
In the video live-streamed by Tarrant, a man inside a mosque appears to say: "Welcome brother", as a gunman approaches. "There are obviously questions being asked of how this person was able to enter the country and undertake this act of terror", the premier said.
ReutersA New Zealand judge ordered that Tarrant's face be blurred to preserve fair trial rights.
Police say they will continue guarding mosques around the country until further notice. No images have emerged from there.
Aziz said: "He gets into his vehicle and I just got the gun and threw it on his window like an arrow and blasted his window".
Ardern's office said the suspect sent the "manifesto" by email to a generic address for the prime minister, the opposition leader, the speaker of the parliament and around 70 media outlets just minutes before the attack.
"It is clear that this can now only be described as a terrorist attack", said Ardern.
Police said three people were in custody.
Twelve operating theatres worked through the night on the more than 40 people wounded, said hospital authorities.
Two other suspected accomplices have also been arrested.
Four people died en route to hospital.
Of the 50 wounded, 36 remain in hospital with 11 in a critical condition.
A few hundred demonstrators have protested the New Zealand mosque shootings outside Istanbul's Hagia Sophia - a Byzantine-era cathedral that was turned into a mosque and now serves as a museum.
The attack came during Friday prayers when the mosques were filled with hundreds of worshippers.
The victims of Friday's shooting included immigrants from Jordan, Saudi Arabia, Turkey, Indonesia, and Malaysia. Muslims account for just about one percent of New Zealand's population.
"I'm not sure how to deal with this".
Another victim, Haji Daoud Nabi, died trying to save a fellow worshiper, his son told an Australian newspaper.
Naeem migrated to New Zealand with his family in 2009 and was a teacher.
The video of Ardern's press conference in Wellington was published online by local broadcaster.
It is customary in Islam to bury the dead within 24 hours but no bodies have been released because of the investigation, police said. "There were two semi-automatic weapons and two shotguns".
"I'm advised that there were five guns used by the primary perpetrator..." "There have been attempts to change our laws in 2005, 2012, and after an inquiry in 2017".
"The United States strongly condemns the attack in Christchurch". All the weapons were legally obtained.
Mass shootings and violent crime are rare in New Zealand, a country of almost 5 million people.
The Pacific Islands Association of non-governmental Organisations (PIANGO) also expressed its "heartfelt grief and sorrow" over the attacks.
US President Donald Trump, who condemned the attack as a "horrible massacre", was praised by the accused gunman in a manifesto posted online as "a symbol of renewed white identity and common purpose".
Tarrant stated that hat he was "from a regular family" and that he "decided to take a stand to ensure a future for my people", the alleged terrorist wrote of his background.
"You may have chosen us", Ardern said, addressing the suspect.
According to New Zealand Police Commissioner Mike Bush, the shooter had "category-A" license.
Pence also affirmed USA cooperation in ensuring all the perpetrators were brought to justice.