data={{1,4.8},{2,8.8},{2,8.0},{3,7.9},{4,11.9},{5,14.4},{6,14.1},{6,15.8},{7,15.6},{8,17.8},{9,18.2},{9,17.1},{10,18.8},{10,19.5},{11,18.9},{12,21.7},{12,21.9},{13,23.8},{14,26.9},{14,25.1}};

Export["Fish.tsv",data,"TSV"]