The Full Guide to the BEST FISH For AQUARIUM in FISCH
The key to unlocking astronomical passive wealth, the BEST FISH FOR AQUARIUM in Fisch, awaits in FISCH. As a seasoned player who achieved Quad-Billionaire status mainly with optimized Aquariums, I can attest they are so overpowered for generating truly effortless and continuous income. The exact species, locations, and mutations required to transform your Aquarium into a powerhouse are explained in this guide on how to maximize your earnings without active fishing.

BEST FISH For AQUARIUM in FISCH: Understanding Value
For BEST FISH For AQUARIUM in FISCH, to really pay off, you have to do much more than just fill it with fish. The value isn't in the size of the fish, but in its mutation and rarity. We'll be going for fish that carry the highest multipliers.
Highest-Ranking Passive Income Mutations
The high-tier mutations greatly raise the base value of a fish to multiply the passive income made in the Aquarium. The following are the traits that you should be hunting:
Try Hard: The large multiplier involved with carrying makes any fish carrying it highly sought after.
Mustard: A consistently strong mutation that greatly increases base value.
Mossy: Generally found together with Mustard; adds a lot of value when together.
Dark: One of the rarest mutations, really enhancing the value of the fish.
High-Value Acquisition Methods
Since these high-multiplier mutations are hard to get in nature, you need to utilize certain places and community strategics:

Admin Abuse Location: This unofficial area is actually the most reliable spot to get the best fish for your Aquarium possible. You must target this area repeatedly to maximize your chances of getting rare mutations such as Try Hard.
The Forgotten Temple constitutes the sole reliable spot to fish for the Mossy and Mustard species. Thus, it is an obligatory destination for acquiring the specific value-enhancing fish.
Black Market: High-risk, high-reward, the Black Market is where overpowered, high-mutation fish tend to appear. Normally due to earlier exploits and duplication, you are able to purchase highly valuable fish without the grind.
Optimizing Rods and Locations
The type of rod and fishing location a player chooses directly influences the mutation rate and rarity of the fish encountered; choosing the wrong gear is a surefire way to waste time.
Rods Built for Mutations
To maximize the chance of hooking a high-multiplier fish, you need rods known for increasing mutation rates:

Luminose and OATH Rod: This is an important combination. It yields a steady mutation rate, and together with good bait, it gives you a great 60x multiplier on the catches.
Serenade Rod: A rod highly recommended for players who want to target maximum compound mutations.
Evil Pitchfork / Chaotic Rods: These are the very best in catching the rarest fish with highly sought-after mutations.
You should focus on doing all Daily Quests and opening Loot Boxes if you don't have these rods, to get the required materials or the rods themselves as soon as possible.
The Forgotten Temple: A Mandate for Mustards
The Forgotten Temple is the single best spot for passive income optimization due to its unique inhabitants.
You must fish here for Mossy and Mustard species.
The fish here spawn frequently, thus making farming easy and efficient.
Use your Luminose and OATH Rod here for the best chance of landing a high-mutation Mustard species.
The Secret to Max Value: The Treasure Appraiser
Just throwing a high-mutation fish straight into your Aquarium is great, but that leaves a lot of money on the table. The real trick to true Quad-Billion status is the Treasure Appraiser—a feature overlooked by many players early on.
Treasure Appraiser is an NPC on Treasure Island. You will have to go to him prior to putting any valuable fish in your Aquarium.
The Appraisal Process:
Find the Appraiser: Make your way to Treasure Island and find the Treasure Appraiser NPC.
Invest: Use a high-value, high-mutation fish in your inventory, such as a Ghost Fish or Teva, or any other rare fish.
Improve Value: Invest gold in the fish repeatedly. The Appraiser can increase the value of the fish permanently by as much as two times the normal amount (often 1.6x or 2.0x on a good roll).
It's a process that literally doubles the passive income your Aquarium generates from that specific fish. If you catch a rare fish valued at 1 Million, an Appraiser roll can turn it into 2 Million in your Aquarium - instantly doubling your passive income stream. Always Appraise before deploying your best fish.
The goal is simple: fish for the highest mutation multipliers, use the best rods, and always double the value at the Treasure Appraiser. This order will greatly speed up the process.
To get the BEST FISH for AQUARIUM in FISCH, which will you target first of these high-value mutations: Try Hard or Mustard?


