Harpoon a Fish: How to Get Better Fish on Roblox

In Harpoon a Fish, a “better” fish is the one that earns more cash per second in your aquarium. You don’t get those by firing at whatever swims past. You get them by stacking a few systems at once: mutation bonuses, Voidstorm weather, getting fat enough to sink deeper, and keeping enough aquarium slots open to show off your best catches.

Quick answer: Equip a mutation item such as the Purple Drill, dive during a Voidstorm, fill your bag, then return, eat food, buy an aquarium slot, and press Equip Best. Your $/sec counter should rise.

What makes a fish better in Harpoon a Fish

Every catch has a rarity tier and a weight, and some catches also carry a mutation in their name. All three show up on the catch card. The rarity tag alone can mislead you. A Molten Octopus labeled Common came in at 1,939kg, far heavier than anything else in the same dive.

Fish	Rarity	Weight
Shadow Prawn	Common	37kg ($3/s)
Rainbow Trout	Common	95kg
Tidepool Blenny	Common	103kg–106kg
Voidstorm Tidepool Blenny	Common	216kg
Molten Octopus	Common	1,939kg
Voidback Tigershark	Mythic	—

Compare the two Blennies. The regular Tidepool Blenny weighed about 103kg. The Voidstorm version, caught during the Voidstorm event, weighed 216kg, roughly double. Mutations are how a common fish becomes a valuable one. That is why the gear and weather below matter more than chasing a rarity label.

Mutation chance: Purple Drill and Voidstorm

Two things raise your odds of pulling a mutated fish. Both are easy to miss.

Purple Drill: equipping it shows Equipped Purple Drill! and +1% Mutation Chance!.
Voidstorm: a server-wide banner reads VOIDSTORM ACTIVATED! along with a VOIDSTORM MUTATION TIME: 5:00 timer.
Fish caught during that window can come back with the Voidstorm prefix, like the Voidstorm Tidepool Blenny.

The Voidstorm timer starts at five minutes. If you see the banner, dive right away instead of spending that time on your island.

The dive loop for better catches

Each run follows the same order. Gear up on the shore, harpoon until the bag is full, then cash in on your island.

Walk to the shoreline on your island and equip the Purple Drill. Wait for the +1% Mutation Chance! message to confirm it is active.

Press DIVE to drop into the ocean. Timing this to a Voidstorm stacks the event’s mutation window on top of the drill’s bonus.

Equipping Drill & Diving — Equip the Purple Drill at the shoreline before you press DIVE, so the mutation bonus applies to the whole run. Shown at 00:36 in VendoPlus’s video. Image: FirstTry

Move your mouse to place the circular harpoon reticle over a fish and click to fire and reel it in. Areas like the Shipwreck hold several fish at once, so you can chain catches quickly.

Harpoon Diving Mini-game — The harpoon reticle follows your mouse. Line it up on a fish and click to reel it in. Shown at 00:44 in VendoPlus’s video. Image: FirstTry

Aim at golden treasure chests on the seafloor too. They reel in the same way fish do, and chat announces chest openings, such as TREASURE CHEST IN BONE has opened!.

Keep harpooning until the bag counter hits its limit. The bag holds five catches at the base size. When it is full, the game shows BAG FULL! FEED YOUR FISH!.

Catching Fish & Chests — A Molten Octopus lands with the bag at 4/5. One more catch and you need to head back. Shown at 01:39 in VendoPlus’s video. Image: FirstTry

Press Space when the PRESS SPACE TO RETURN prompt appears. This takes you back to your island with the whole bag.

Keep an eye on chat while you dive. Spawn alerts like A MYTHIC Sawfather spawned in Lava! tell you when a high-tier fish appears in a specific zone.

Eat food to sink deeper

Your size controls where you can go. Eating food, such as the burgers on your island, makes you fatter, and more weight lets you sink into deeper water where rarer fish and sea monsters live. The Food counter climbs as you eat. One session took it from 106 to 122.

Treat eating as part of every return trip, not something to do when you’re bored. If you can’t reach the depth you want, the fix is more food before the next dive. Repeated forced attempts won’t get you there.

Aquarium slots and Equip Best

A great fish earns nothing sitting in your bag. Only fish placed in your aquarium make passive cash, and the number of slots caps how many you can display. Upgrade from the aquarium wall display on your island. Each purchase adds one slot and confirms with Aquarium UPGRADED! (+1 slot).

Button	Cost
`+1 EQUIP [$500]`	$500
`+1 EQUIP [$5K]`	$5,000 (5th active slot)
`+1 EQUIP [$50K]`	$50,000

Prices jump tenfold each step, so the $50K slot takes a while. Once a slot is open, press Equip Best. The game fills your slots with your highest-earning fish automatically, which saves you from comparing catch cards by hand. If you see Aquarium Full, you need another slot before a new fish can go in.

Managing Aquarium Slots — The aquarium panel holds both controls you need: buy a +1 slot, then hit Equip Best to fill it. Shown at 00:24 in VendoPlus’s video. Image: FirstTry

Robux shortcuts exist if you’d rather pay. A +10 BAG upgrade costs 149 Robux and lets you carry more catches per dive. 2X FAT costs 249 Robux. You can also use a Bag Potion, but only one at a time, since the game blocks a second with A Bag Potion is already active!.

How to confirm your fish are better

The proof is the income counter. After equipping new catches, you should see messages like Successfully equipped Molten Octopus! or Successfully equipped 2 fish!, and your cash-per-second figure should rise. In one full loop, a Voidstorm dive plus two slot upgrades moved an island from $33/sec to $99/sec.

Returning & Upgrading Capacity — After the return trip, a new slot and Equip Best put fresh catches on display, and the $/sec counter climbs. Shown at 01:58 in VendoPlus’s video. Image: FirstTry

If the number didn’t move, your new catches didn’t beat what was already displayed. That’s your cue to eat more, dive deeper, and try for a mutation on the next run. Once you hit the slot cap, the next jump comes from replacing weak fish, not adding more.