Rabbieh Haddara, 26, pleaded guilty to a string of charges, including drug trafficking, selling high-powered assault rifles and possessing protected wildlife without a licence.

County Court judge Liz Gaynor said when Haddara was arrested at his Essendon home in May 2012, he had a one-year-old freshwater crocodile in a fish tank in his living room; a Sterling .22 calibre rifle in a television unit; .22 calibre rounds of cartridge ammunition in kitchen drawers; two .22 calibre pen pistols in his car; a large metal sword with jagged edges in a kitchen cupboard; a crossbow in the master bedroom; and three Samurai swords on a kitchen bench.

Judge Gaynor said that before his arrest, Haddara had checked into a hotel in Southbank for more than two months, paying $25,475 in accommodation fees while he was dealing drugs and selling guns.

Haddara, a father of two who began using amphetamines at the age of 15, went to Bayside High School in Altona North but habitually skipped class, fought with other children and was repeatedly suspended. He left school functionally illiterate.

"Your inability to read and write apparently being missed by teachers and you, in fact, paying other students to complete assignments for you," the judge told Haddara on Wednesday.

Judge Gaynor said there had been some difficulty during Haddara's earlier plea hearing when psychologist Tim Watson-Munro claimed testing had revealed Haddara was intellectually disabled.

The judge said she had some concerns with this assessment given the clearly leading organisational role Haddara had played in criminal activity involving the supply of drugs and firearms.

So Haddara was further tested by Forensicare principal consultant psychologist Professor Michael Daffern who found he "intentionally chose incorrect answers for some of the items in an effort to appear impaired".

Professor Daffern said Haddara's intellectual ability was "well below average but it is highly unlikely that his level of intellectual functioning is in the intellectually disabled range”.

"You apparently described to Professor Daffern distorted sensory experiences, including visions when you were falling asleep, noises in your cell and a history of “auditory and visual perceptual abnormalities when intoxicated with amphetamines,” the judge told Haddara.

"Following the testing administered by Professor Daffern, I am not prepared to accept ... that you have an intellectual disability or that you were suffering from a major depressive disorder at the time.

"I accept that you are a relatively young man, that this is your first experience of prison and that it has been extremely difficult for you.

"However, you have committed very serious offences in terms of the trafficking, which is at the high end of the scale, and, in particular, in relation to your sale of sinister and highly destructive firearms.

"Whatever lay behind your offending, Mr Haddara, I have no doubt that you were engaging in continuous, extremely criminal and very dangerous offending which posed a large threat to the community overall, particularly in so far as the sale of firearms was involved.

"The damage that can be inflicted by the assault rifle and the carbine alone is immense."

Haddara was jailed for seven years with a non-parole period of four years and six months.