[mayoff]

Antimatter also has anti-color-charge. Quarks have a ‘color charge’ (unrelated to visible colors) which is ‘red’, ‘green’, or ‘blue’. An antiquark is antired, antigreen, or antiblue (and has the opposite electrical charge from its corresponding normal quark).

https://en.wikipedia.org/wiki/Color_charge

[phkahler]

Could anti-quarks behavior be explained by them having negative mass instead?

[KMag]

That would require a re-formulation of conservation of color charge. You could probably come up with an alternative formulation where everything is consistent, but all of the formulas would almost certainly be more complicated. The most obvious way would end up replacing color by the sign of mass times color everywhere, but then you've just renamed ant-red, anti-blue, and anti-green, with no obvious benefit.

[monocasa]

I don't believe so; color charge isn't a scalar like mass is.