Fish is the 102nd episode of Thomas and Friends.
A special load of fish is ordered and extra vans are needed for The Flying Kipper and, to Henry's frustration, the only vans available are old and unused. Duck shunts them into position and moments later, Thomas arrives with the post train and he warns him to take care, reminding him of his own experience with fish. Henry is still complaining about his extra load, but his driver tells him that at least another engine will be there to help them.
At Wellsworth, Duck waits for Henry and when he arrives, he moves to the back to help him to the top of Gordon's Hill without getting coupled up. As the train nears the top of the hill, Henry begins to inadvertently pull away from Duck while the tail lamp on the last van falls off in the process. Worse still, Henry slows down while Duck suddenly loses sight of the train and tries to catch up, but accidentally crashes into the last van causing loads of fish to spill out.
The mess is cleaned up later that morning and the fallen tail lamp is found at the bottom of the hill. The Fat Controller tells Duck that the accident was not his fault and that the crew should have fitted the tail lamp on properly, and assures him that he will be in working order again. Duck reflects that Thomas' earlier advice about fish was right.