There are two potential routes for 100%: "Fresh File" and "NG+". Fresh File must be done from a new save file, while NG+ allows the use of an existing save file that has 0/60 Starfish colllected. The main benefit of NG+ is the ability to skip cutscenes, and having the dart unlocked at the start of Going to School (though at the cost of the level ending a couple seconds slower).

When setting up an NG+ file, play each level the same as an Any% run to set a time record that likely won't be beaten when going for all the Starfish. The only difference is that you must actively avoid winning the races in Going to School and Whale Chase. You'll also want to do a run of each level where you aim for a high Shell Score, as beating that score will cause a few seconds of timeloss.

When doing the actual run, NG+ players should do each Bonus Level as they are unlocked. Earning a Starfish from a previously finished level will highlight the Bonus Level automatically. Fresh File players, meanwhile, should play through all main levels first, as finishing a level for the first time automatically highlights the next level regardless of Starfish status. Once you've finished Fishing Net Rescue, play through each Bonus Level in reverse chronological order (i.e. FNR Bonus, TP Bonus, WC Bonus, etc.), grabbing any main level Starfish you missed along the way. This does make Field Trip Bonus more of a late run killer than an early run killer, but saves several seconds on menu navigation.

Starfish progress will not reset when you die, the only exceptions being the Bounce Bonuses in Minefield, Field Trip Bonus, and Training With Gill Bonus. While completion of every level in order is required regardless of which route you take, completion of levels is not required to collect Starfish on return visits. As soon as the Starfish spawns, you can exit the level through the pause menu and the Starfish will be saved, skipping the Starfish cutscene and the rest of the level. This does not apply to Bonus Levels, however, and is only useful when backtracking. Perhaps it could be used in a separate "All Starfish" category, but that's neither here nor there.

Now for a few level-specific tips:

• In Hide and Seek, find Bubbles, Deb and Peach first, then go to the left, saving Gurgle for last.
• In Mask Search, defeat Clams 6-8 after reaching Marlin, so the timer doesn't interfere and force you to restart. Also, try to get every Starfish as Dory, as her Starfish cutscene is half as long as Marlin's.
• In Anglerfish Chase, just mash the Move button (X on PS2 or A on Xbox/GCN) and you'll automatically get all the Bubble Rings. You may want to avoid the first Shell Ring if you're doing Fresh File, though.
• In Fishing Net Rescue Bonus, you'll want to deposit the Green Pebble last, which can only be done with Nemo.