This is from Harris Farm Marrickville NSW. Not sure of the full details.
A whole Tasmanian Salmon $15.99 per kg. Under 2kg. Comes up to $30 per fish.
They will clean and cut however you want. Usual price about $30 plus per kg. So about 50% off. Saw some Deboned Tasmanian Salmon Fillets from selling at $65.99 per kg as a price comparison.
Harris Farm is available in NSW, QLD and ACT. i am not sure if its available every store.
Most likely store exclusive as it's showing as $19.99/kg online
Also the link to your imgur image is empty.