a couple of times I had a to re-home some large fish, I doubled up the black trash bags and lined a cardboard box with them. the guy then just picked up the cardboard box. works well, no problems. just heavy.
I did this to transport fish before. Filled about 40 gallons in a bag. But u cant pull the bags out they will just bust open. Might work if u triple up the bags.
Aside from the occasional defect, which you'll find in any product, Lawn and Garden bags and especially Contractor grade bags are tough enough to last a while, and shouldn't be any problem for transporting fish. I have never seen them scented with anything. The primary issue would be the same thing you get with any plastic bag and big fish/catfish; fin punctures.