A stablehand banned over the 'Aquanita eight' doping scandal has denied being involved in giving horses illegal "top-ups" on race days or knowing about the cheating scheme.

Truck driver Daniel Garland said he had no idea why he was mentioned in texts sent by other members of the Aquanita eight and what they were talking about in the messages.

Forced to give evidence as four trainers appeal their disqualifications, Garland maintained he knew nothing about the conspiracy to cheat in more than 100 races over seven years by giving horses top-ups of sodium bicarbonate and Tripart paste.

Racing Victoria barrister Jeff Gleeson QC accused Garland of lying.

"You were involved in the administration of bicarb routinely over this whole period," Gleeson said.

Garland replied: "No, I wasn't."

Gleeson later said: "It's becoming pointless for you to resist the suggestion that what was going on at Aquanita was the systematic administration of bicarb to horses."

Garland replied: "No, it didn't happen. As far as I'm concerned it didn't happen."

Garland said he never took syringes with sodium bicarb to any race track nor administered it to any horses.

Eight people associated with thoroughbred management company Aquanita Racing were disqualified over the top-ups scheme, with Garland banned for a year after being deemed to be well down the hierarchy of command.

Much of the stewards' case relied on 1000 text messages found on stablehand Greg Nelligan's mobile after he was caught inserting a syringe into the Robert Smerdon-trained Lovani's mouth on Turnbull Stakes day in October 2017.

The Victorian Civil and Administrative Tribunal on Thursday heard Garland featured in a number of texts sent by other people, who referred to him by the nickname "Moth".

Nelligan sent texts to his wife Denise in May 2013 saying stewards had been around, "Moth a mess" and "worried getting caught".

A month later Nelligan told his wife: "Moth stressing and all of us. I think he half wants to get caught."

Garland denied that referred to him being stressed about being caught administering sodium bicarbonate to horses.

He said he had no idea what the Nelligans were talking about in the texts.

The inquiry heard Smerdon told Nelligan in a June 2010 text that he needed a couple of top-ups for Moth to take to Warrnambool, but Garland said it never happened.

"I've never been involved in it," Garland said.

"It doesn't look good but I can assure you it didn't happen."

Garland said the term top-up only referred to feed and water and had nothing to do with sodium bicarbonate.

He said he would not administer bicarb to a horse on race day even if asked by a trainer.

Smerdon, who was banned for life, and trainers Stuart Webb (four years), Tony Vasil (three years) and Liam Birchley (one year) are fighting their disqualifications.

The hearing will resume on Monday, when the Nelligans have to appear after being subpoenaed.