Everytime a guest looks at a tank there is a chance that every species will give you prestige. The chance are calculated using these variables:

• How big is the fish? (Before it grows)
  
• How many of each fish are in the tank?

For instance every (single) fish size 2 gives you 32 % chance that you get prestige when a guest looks at it.

• Size 3, 35%
  
• Size 4, 37%
  
• Size 5, 37%
  
• Size 6, 40%
  
• Size 7, 42%

You can find the prestige from hovering over the prestige symbol with your mouse.

There are exeptions to this rule:

• Dislike conspecifics
  
• Congeners only
  
• Shoalers

These fish gets a bonus to the %. Especially "Dislike conspecifics" gets a huge bonus. This you can exploit (Read on)

Dislike food competitors or light does not give any bonus.

By adding more of the same fish in each tank, the chance of getting prestige increases.

Prestige for size 10 fish:

• 1 45 %
  
• 2 60 %
  
• 3 70 %
  
• 4 79 %
  
• 5 85 %
  
• 6 91 %
  
• 7 95 %
  
• 8 99 %
  
• 9 100 %

That means you need 9 fish to be 100 % sure that this fish will give you prestige everytime a guest looks at the tank.

The thing is, to increase your chance of getting prestige for a species you need to add more of them to a tank.

But for a Bull Huss, size 10 when young, you need a tank size 305 to be 100 % sure to gain prestige.

That will be very hard to do with the big fishes, as you will have a hard time feeding them.

So settle for less, maybe 70-80 %? Then there is a little trick:

4 Bull Huss in one tank, gives you a 79 % chance of getting prestige. If you settle for 79 %, then you only need a size 140 tank.

But if you instead add 1 Bull Huss into three different tanks you get 83 % chance of getting prestige. And then you only need a size 105 tank.

Why is that? (The simple math)

First tank there is 45 % chance of getting prestige. So if 100 guests, there are 45 of them that gives you prestige. The last 55 guest have a 45 % chance of giving you prestige next time they see a Bull Huss. So 25 of these 55 guests will give you prestige on tank 2. Leaving 30 guest back. On the last tank (number 3) 45 % of the 30 guest will give you prestige. So all in all 83 guest will give you prestige if you put 3 Bull Huss in 3 different tanks.

If you put 3 in one tank, you only get 70 %.

The same calculations can be made on rocks, plants and theme decorations.

But as most of you probably noticed, guest get tirred of seeing the same decorations multiple times. The same goes with fish.

So if you put in every species/decoration in every tank, you will get negative prestige.

Always look at the guest thoughts.

First you will see that guest says : Ive already seen Bull Huss
This doesnt give you negative prestige, its more like a warning.

Next you will see that guest says: Im getting bored of seing Bull Huss
And then you will get negative prestige.

So always look at the guest thoughts.