Statements: All fishes are grey in colour. Some fishes are heavy. Conclusions: 1.All heavy fishes are grey in colour. 2.All light fishes are not grey in colour.

Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, it follows that 'Some heavy things are grey in colour'. I is a cumulative result of this conclusion and the first premise. Thus, only I holds.