Answer:
The greater integer is -3.
Explanation:
As the problem indicates that fishes are below sea level, you take into account that sea level is 0 feet, and from there, as they are below, you mark their positions as negative integers.
See picture below where fishes position is marked. You can see there that the fish that is in position -3 is the number nearest 0, so -3 is greater than -4.