Fisch Calculator — Calculate Catch Probability, Rod Luck & Fish Value Instantly

Master Roblox Fisch with the most accurate Fisch calculator. Compute catch probability, estimated attempts, rod luck multipliers, bait bonuses, and weather effects for every fish rarity.

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Fisch Catch Probability Calculator

Select fish rarity, rod type, bait, and weather to calculate catch probability, estimated attempts, and expected fish value in Roblox Fisch.

Select fish rarity, rod, bait, and weather, then click Calculate Catch Stats to see results.

Fisch Catch Probability Formula Explained

The Fisch catch probability formula calculates your chance of hooking a specific fish rarity based on your rod's luck multiplier, active bait bonus, and current weather conditions in Roblox Fisch.

Final Probability = base_rate × rod_luck × (1 + bait_bonus + weather_modifier)
Expected Attempts = ceil(1 ÷ Final Probability)

Rarity Base Rates & Value Multipliers

RarityBase RateValue MultiplierAvg. Value (10 lb fish)
Common45%1×~50 coins
Uncommon28%2.5×~125 coins
Rare16%6×~300 coins
Epic7%15×~750 coins
Legendary3%35×~1,750 coins
Mythic1%80×~4,000 coins

Base value per pound is approximately 5 coins. Higher rarity fish multiply this base value dramatically, making Mythic catches exceptionally valuable.

How Fisch Catch Mechanics Work in Roblox Fisch

Understanding the layered catch system is essential for optimizing your fishing strategy. Follow this framework to maximize rare fish catches:

  1. Identify your target rarity — Each rarity has a distinct base probability. Mythic fish are 45× rarer than Common fish at base rates.
  2. Equip the right rod — Your rod's luck stat directly multiplies the base probability. A Trident Rod triples your chances compared to a Flimsy Rod.
  3. Apply effective bait — Bait provides percentage bonuses: bait_bonus = bait_percent ÷ 100. Shark Bait adds a substantial 30% boost.
  4. Check weather conditions — Weather modifies your overall catch rate. Rainy weather boosts catches by 12%, while Storm conditions penalize by 20%.
  5. Compute final probability — Multiply base rate by rod luck, then apply the combined bait and weather modifier.
  6. Plan your attempt count — Divide 1 by your final probability to estimate how many casts you'll need on average.

Fisch Catch Probability Calculation Examples

Example 1: Common Fish with Flimsy Rod

Rarity: Common — Rod: Flimsy (1×) — Bait: Worm (+8%) — Weather: Clear (0%)

Probability = 45% × 1.0 × (1 + 0.08 + 0) = 48.6%
Expected Attempts = ceil(1 ÷ 0.486) = 3 attempts

Example 2: Epic Fish with Carbon Rod

Rarity: Epic — Rod: Carbon (1.6×) — Bait: Shrimp (+15%) — Weather: Rainy (+12%)

Probability = 7% × 1.6 × (1 + 0.15 + 0.12) = 14.22%
Expected Attempts = ceil(1 ÷ 0.1422) = 8 attempts

Example 3: Mythic Fish with Trident Rod

Rarity: Mythic — Rod: Trident (3×) — Bait: Shark Bait (+30%) — Weather: Rainy (+12%)

Probability = 1% × 3.0 × (1 + 0.30 + 0.12) = 4.26%
Expected Attempts = ceil(1 ÷ 0.0426) = 24 attempts

Weather Effects & Fish Mutations in Roblox Fisch

Weather plays a critical role in determining both catch probability and the likelihood of encountering mutated fish. Mutations are special fish variants with unique visual effects and significantly higher sell values.

Weather Modifier Reference

  • Clear — No modifier (0%). Standard fishing conditions.
  • Rainy — +12% catch bonus. Also increases mutation chance by approximately 5%.
  • Foggy — +5% catch bonus. Slightly increases the chance of Ghost mutation fish.
  • Windy — −8% catch penalty. Increases chance of Big mutation by 8%.
  • Storm — −20% catch penalty. Rare event that significantly boosts Electric and Charged mutation odds.

Common Fish Mutations

Mutations multiply a fish's base value on top of the rarity multiplier. A Mythic fish with the Golden mutation can be worth over 200× the base value of a Common fish.

Total Value = base_value × rarity_multiplier × mutation_multiplier × weight

Popular mutations include: Shiny (2× value), Golden (3×), Electric (2.5×), Ghost (2×), Big (1.5× to 3× depending on size), and Charged (4×).

People Also Ask About Roblox Fisch

Catch probability in Fisch is determined by multiplying the fish rarity base rate by your rod's luck multiplier, then applying bait bonuses and weather modifiers. Common fish have the highest base rate around 45%, while Mythic fish have only about 1% base probability. Better rods with higher luck stats significantly improve your chances of catching rare fish.
The Trident Rod offers the highest luck multiplier at 3×, making it the best choice for catching Legendary and Mythic fish. The Mythic Rod follows closely at 2.5× luck. Pairing a high-luck rod with Shark Bait (+30% bonus) and fishing during Rainy weather (+12% modifier) maximizes your chances of landing rare catches.
Bait provides a percentage bonus to your catch rate: Worm gives +8%, Shrimp +15%, Magnet +20%, and Shark Bait +30%. Weather also modifies catch probability—Rainy weather adds +12%, Foggy adds +5%, Clear weather has no effect, Windy reduces by 8%, and Storm conditions reduce catch rates by 20%. These modifiers stack with your rod's luck multiplier.
With a base probability of 1% for Mythic fish, you'd expect around 100 attempts without any bonuses. Using a Trident Rod (3× luck), Shark Bait (+30%), and Rainy weather (+12%), your probability increases to about 4.26%, reducing expected attempts to roughly 24. Without premium gear, catching Mythic fish requires significant patience and hundreds of casts.
Roblox Fisch features six fish rarity tiers: Common (45% base rate, lowest value), Uncommon (28% base rate), Rare (16% base rate), Epic (7% base rate), Legendary (3% base rate), and Mythic (1% base rate, highest value). Each tier multiplies the fish's base value—Mythic fish can be worth over 80× more than Common fish of the same weight class.

Frequently Asked Fisch Calculator Questions

Yes. The calculator includes all six fish rarity tiers available in Roblox Fisch: Common, Uncommon, Rare, Epic, Legendary, and Mythic. Each rarity uses its specific base catch probability and value multiplier to ensure accurate calculations for every fish type.
The expected attempts estimate is a statistical average based on probability theory. It represents the mathematical expectation—meaning over many fishing sessions, your average number of attempts will converge toward this number. Individual sessions may vary significantly due to the random nature of each catch.
The primary calculator focuses on catch probability and fish value. For mutation-specific estimates, refer to the Weather Effects & Fish Mutations section which explains how each weather condition impacts mutation chances. Combining catch probability with mutation rates gives you a complete picture of your expected rare fish outcomes.
This calculator focuses on the core mechanics of rod luck, bait, weather, and fish rarity. Time of day and seasonal effects may introduce additional modifiers in specific game updates. For the most current information, cross-reference results with the latest Fisch patch notes and community resources.
Yes. The NumbrWiz Fisch calculator is completely free with no registration required. All calculations run client-side in your browser. No data is collected, stored, or transmitted. You can use it unlimited times to plan your Roblox Fisch fishing strategy.
Absolutely. By calculating expected fish values across different rarities, you can make informed trading decisions. The value estimates help you understand whether a trade offer is fair based on the rarity multipliers and estimated market values of the fish involved.

Roblox Fisch Glossary

Fish Rarity

The tier classification of a fish determining its base catch probability and value. Six tiers exist: Common, Uncommon, Rare, Epic, Legendary, and Mythic.

Rod Luck

A multiplier stat on fishing rods that directly scales the base catch probability. Higher luck rods like the Trident Rod (3×) dramatically improve rare fish chances.

Bait Bonus

A percentage addition to catch rate provided by equipped bait. Shark Bait offers the highest bonus at +30%, stacking with weather modifiers.

Weather Modifier

An environmental factor that adjusts catch probability. Rainy weather grants +12%, while Storm conditions impose a −20% penalty on all catches.

Expected Attempts

The statistical average number of casts needed to catch a specific fish, calculated as the ceiling of 1 divided by the final catch probability.

Fish Mutation

A special variant of a caught fish with unique visual effects and multiplied sell value. Common mutations include Shiny (2×), Golden (3×), and Charged (4×).

Value Multiplier

The factor by which a fish's base value is multiplied based on its rarity. Mythic fish have an 80× multiplier, making them vastly more valuable than Common fish.

Base Value

The foundational coin value of a fish before rarity and mutation multipliers, approximately 5 coins per pound of fish weight in Roblox Fisch.

Editorial Review & Methodology

This Fisch calculator was built and reviewed by the NumbrWiz Editorial Team. The catch probability formulas, rarity base rates, rod luck multipliers, bait bonuses, and weather modifiers are based on comprehensive analysis of Roblox Fisch gameplay mechanics, community-verified data, and cross-referencing with official game documentation where available.

  • Formula verification: Cross-checked against community data sources, player guides, and in-game testing where possible.
  • Edge case testing: Tested with all six rarity tiers, all five rod types, all five bait options, and all five weather conditions.
  • UX review: Designed for intuitive input with clear validation, step-by-step breakdown, and accessible result presentation.

Transparency note: All calculations run client-side in your browser. No data is ever collected, stored, or transmitted. This is an unofficial fan utility tool. Results are for planning and educational purposes; actual in-game values may vary with updates. Verify critical calculations independently.

Page last reviewed: May 2026 · NumbrWiz Editorial Team