2, the difference between grass carp and mackerel.

3, mackerel and grass carp which grows faster.

4, is mackerel grass carp more spiny.

1. Mackerel has fewer thorns compared to grass carp.

2. From the point of view of the specific distribution of fish spines in the two bodies, the main spines are they both have.

3. These spines are generally larger and located in the center of their bodies, which is more obvious and can serve a greater purpose.

4. The difference is the small spines between the muscles of the two, which are not many in cyprinids and are more numerous and distributed in a more disorganized manner in grass carp.

5. So overall, mackerel has fewer spines than grass carp.