Tilapia imports are heavily restricted to Australia, The live fish will not be allowed, they are considered "restricted noxious fish".

The rules are:

Illegal to Keep: You cannot keep tilapia (dead or alive), sell them, give them away, or use them as bait.

Immediate Euthanasia: Humanely kill the fish as soon as you catch it.

Disposal:

Bury: Bury them deep and well away from the water's edge to prevent scavengers from dragging them back in or floodwaters from releasing eggs.

Bin: Place them in a rubbish bin.

No Filleting: You cannot take fillets and dispose of the rest; the entire fish must be destroyed.

Various state departments have hotlines for reporting tilapia.

There are different hotlines per state:

Queensland Department of Agriculture and Fisheries (DAF) (13 25 23)

New South Wales Department of Primary Industries (DPI) (1800 675 888)

Victoria (VFA) Reporting hotline (13FISH or 13 34 74)

Western Australia Dept. of Primary Industries & Regional Development (1800 815 507)

I've had rewards for reporting them (fishing reel, free bait, etc).

For those that don't know why, and I didn't, the reason for this is that Tilapia are "mouth brooders", that is they keep the fertilised eggs in their mouth. So throwing away a dead female can cause these eggs to hatch, and reinfect the waters with new Tilapia.

I also hear you can dispose of them by placing them in a pan with fresh pulverized tomato, garlic, olive oil, basil, then a little lemon juice, oregano then finally, salt and pepper to taste. Highly effective, efficient and delicious.

Where I grew up (in northern Australia) a lot of people targeted and ate tilapia out of local estuaries .. there were a lot of them and they were big.