The confirmed rule
The official Harpoon a Fish description tells players to get fat and sink deeper. That confirms the relationship between successful catches, growing weight, and downward progression. It does not publish a permanent table of exact layer thresholds, so the displayed values and prompts in your current server should guide the route.
Begin by recording your current weight or equivalent visible progression value. Catch one accessible fish, complete the reel, and compare the display. If the value increases, you have a working baseline. Repeat with reliable targets until the game shows a new descent option, route prompt, or clear change in depth access.
A repeatable depth routine
- Join the official FirstTry experience and let the interface load.
- Note the displayed weight and current area or depth label.
- Catch a fish you can land consistently.
- Confirm the catch and recheck the displayed value.
- Secure the catch before spending time in menus when other players are nearby.
- Inspect the route or descent cue after a small group of catches.
- Attempt the next layer only when the live interface indicates that progress is possible.
This routine separates catch skill from a progression problem. If you are missing the target, more route theory will not help. If catches succeed and the displayed value rises, continue until the interface provides the next signal.
Choose efficient catches
Efficiency is not simply the largest-looking fish. A useful target is one you can find, hit, reel, and keep with reasonable consistency. Compare the displayed result of several catches under the same conditions. Use the current measurement rather than visual size or a copied community value.
New Index entries may still be worth taking even when another fish is better for immediate depth. Decide the session goal first. If you are pushing depth, favor repeatability and visible progress. If you are filling the Index, accept a slower route in exchange for discoveries.
Avoid exposing a catch while browsing. Stealing is included in the official description, so a theoretically efficient target becomes inefficient if it is regularly lost before it counts.
Read route and interface clues
Current player walkthroughs describe weight-building and visible depth or island cues, sometimes using a Mukbang-style interaction as part of the route. Treat those details as community observations until the current interface confirms them. Button placement, labels, and exact requirements can move.
Look for explicit text: a required value, locked prompt, depth gauge, highlighted route, or unavailable action. Record the wording. If the game provides no number, do not create one. A message such as “need more weight” supports continued catching but not a precise threshold.
When a route becomes available, note the before-and-after displayed state. That is stronger evidence than remembering where another player appeared to descend.
Why you may be stuck
The weight display does not change
Verify that the fish was fully caught and credited. Reopen the relevant panel and catch one ordinary target as a control. If the value still appears frozen, rejoin a fresh public server. Do not test with a rare fish until the ordinary control works.
The value rises but the route stays locked
Read the route’s live requirement. There may be another progression condition, or the current value may not yet be sufficient. Since a stable first-party threshold chart is unavailable, continue with measured catches or investigate the explicit condition rather than trusting an old number.
You reach the route but cannot descend
Reset the camera and movement, close overlays, and approach the interaction point again. On touch or controller, follow the active prompt. A control problem can look like a progression gate.
Progress disappears after rejoining
Check whether you are comparing the same account state and same type of value. Capture the display before leaving and after rejoining. If the game presents a save or claim action, use only the live instruction; no unsupported persistence rule is assumed here.
Use a progression log
A simple log should include the date, server, starting value, fish name, displayed catch result, ending value, current area, and route message. Leave rarity or rate blank when not shown. After several comparable catches, the log tells you what is efficient in the current build.
Do not turn a handful of catches into a percentage. Random outcomes need a much larger, controlled sample. The purpose of the log is to support your next decision, not to manufacture certainty.
What to do after reaching a deeper area
Pause and establish a new baseline. Catch one manageable target and inspect its Index and progression result. Do not immediately commit an unfamiliar catch to evolution or the aquarium. New areas may introduce entries you have not recorded, and the long-term choice can wait until the result screen is clear.
If the deeper route contains harder targets, return to How to Harpoon for controlled practice. For a new fish, use the Fish Index fields. If you are deciding what to keep, compare Evolution and Aquarium before confirming.
Avoid bad shortcuts
Do not share account access for a promised depth boost, auto-farm, or rare catch. Do not install unknown executors or paste scripts into your client. Apart from account and device risk, an automated result teaches you nothing about the current route and may violate Roblox rules.
Supported codes can add resources, but the official text does not say that a code bypasses every weight or depth requirement. Redeem through the normal in-game field and verify the actual balances.
Sources and check date
- Official Harpoon a Fish Roblox experience — the “get FAT and sink deeper” progression direction.
- Current community walkthroughs checked October 17, 2026 — weight-building and interface cues, used only as observations to verify in game.
- Live game interface — authority for current values, route prompts, layer boundaries, and controls.
This depth guide was checked on October 17, 2026. No fixed threshold is supplied where the official sources do not publish one.