Marlins are one of the biggest fish in-game. They are big in Harry and Peter levels and medium in Goliath levels, but never small, unless you use a Shrinkshroom. They will never come like the barracuda or The Intruder. They first appear in Wrasse Reef. large ones eat herring, john dorys, humphead wrasse and pufferfish and are preyed on by leopard sharks and pelicans. The medium ones eat tuna and are preyed on by orcas. They're drawn out by the Intruder in Jellyfish Jig and Reefo Relaxo before being evicted for the last time in Tricky Treats. They appear 6 times in total, or in 1/10th of the levels.
- Marlins are big as tuna but in Goliath levels, marlins are medium and tuna is small.
- Marlins (in real life) swim up to 80 km/h, but they are slow as other fish.