hey blaban 

the two courses you have mentioned are very different from each others. each has its own job and career opportunities . first talking about fisheries then this is a sector which is less popular but has good jobb opportunity oon the other hand but i will not suggest to comlpete a phd in fisheries . on the other hand zoology is quite famous and demanding course . there is a ot to do after honours in zoology still i will say follow your passion cuz both have some good options 

best wishes