Fish pond not coughing up the goods

Discussion in 'General Discussion' started by Cristi, Mar 28, 2020.

  1. Cristi

    Cristi Void-Bound Voyager

    I'm in winter of my fourth year. My trout pond is three years old, and the fish have been happy all that time. They're supposed to occasionally produce rainbow shells and prismatic shards. I got one rainbow shell in all this time, and never a prismatic shard. Just a lot of roe. Is this normal? Has anyone else tried having rainbow trout in their fish pond?
     
    • Elenna101

      Elenna101 Scruffy Nerf-Herder

      Haven't tried rainbow trout (yet), but let's do some math!

      I'm going to pretend you've had 10 trout in there for all three years, because that's easier than figuring out the average time it takes to get to 9 fish (the point where you start getting shells/shards).
      So they've been producing for 3*4*28 = 336 days.

      According to https://stardewvalleywiki.com/Fish_Pond the chance of any production in one day is (0.15 + 0.08*population) = (0.15+ 0.08*10) = 0.95.

      To get a shell, you need two things to happen: they choose to produce something, and they hit the 2% chance of producing a shell. The probability of this is 0.95*0.02 = 0.019 = 1.9%
      To get a prismatic shard, you need three things: they produce, they don't produce a shell, and they produce a shard (0.1% chance). Thus the probability is 0.95*(1-0.02)*0.001 = 0.000931 = 0.0931%

      Probability of getting 0 shells on 336 days = (1-0.019)^336 = 0.00159 = 0.16%
      Probability of 1 shell in 336 days = 336*0.019*(1-0.019)^335 = 0.0103 = 1.03%

      Probability of 0 shards in 336 days = (1-0.000931)^336 = 0.731 = 73.1%

      So you've gotten super unlucky on the shells, but it's normal not to get any prismatic shards in that time.
       
      • Cristi

        Cristi Void-Bound Voyager

        Wow. Thanks. That's some fancy footwork you done there.

        If I had known all this I would have kept the sturgeon. lol
         

        Share This Page