Answer: 2. Explanation: Let x = day 1 → x + (x+4)+(x+8)+(x+12)+(x+16)=30 → 5x+40=30 → 5x=-10 → no solution with +4 pattern. (Adjust logic: must be +3 daily like original? Then x+(x+3)+(x+6)+(x+9)+(x+12)=30 → 5x+30=30 → 5x=0 → x=0 → no fish? Must reconsider values or error in logic.)