Juvenile Gold Fish First-Colors...dark vs gold — a theory (or just Covid-19 quarantine, super-boredom?)

Mmathis

TurtleMommy
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We’re always getting questions about the color of GF fry/juveniles: Why are some gold-fish juvies gold-colored and some black or dark olive colored at the same stage of life? We all know that the darker color is a way for the young fish to be camouflaged, as a defense against predators. So then, why aren’t all baby GF dark?

Disclaimer: this is not based on a scientific study, but an observation.

While we wait to have our new pond built, I have my GF housed in 2 holding “tanks” in the backyard.

  1. One is a 300 gallon Rubbermaid stock tank (connected to a SKIPPY filter). The bulk of the fish, along with a ton of plants (anacharis and parrot feather) are in this tank. It sits under an oak tree and gets very little direct sunlight — but does get a few hours of afternoon sunlight. This water is crystal clear and on the cooler side. The plants are thriving: green, fluffy, etc., as are the fish. These fish are visible and friendly.
  2. ”Tank” #2 is an Intex pool (not sure about the capacity, but it is al least as big if not bigger than the stock tank). It has about a dozen GF (not sure how many are left after the egret attack), and again, a ton of plants. It sits in the middle of the yard, in direct sunlight almost all day (morning shade). The filter is a box filter with a spray head (and I just hooked up my Oase SwimSkim skimmer). The water in this “tank” isn’t as pretty as the #1 tank. The water temp is a few degrees higher. The plants all look like they’ve seen better days (I occasionally rotate them with the other tank)...and just look sad:cry:. The fish in this one are thriving and getting big! But they are more shy and you only see them if you sneak up.
4573818F-FB71-45CB-9989-B3B328359CEE.jpeg
BTW, water parameters are the same in both tanks.

I have noticed juvenile GF in both tanks. The ones in tank #2 (direct sunlight with sad looking plants) are dark.
The ones in tank #1 (less sunlight, clearer water, healthy plants) are gold.

So, I’m just wondering if the individual environments in the 2 tanks has anything to do with the way first-color manifests itself — as a protective mechanism? The juvie fish that are dark are in the tank (#2) that gets more exposure and has the worst plant coverage. The fish that are gold, are less exposed and have a rain forest of plants for coverage (#1). IOW, the fish in the exposed (#2) tank are more vulnerable to predation, so stay dark longer, while the fish in the “protected” (#1) tank don’t feel as threatened, so don’t go through the dark phase.

IDK, just an observation.
 
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I would agree with you... except we've had both colors n our pond at the same time! And some of my young goldfish stay dark way longer than others. I have one right now that's three years old... still green-black. Others from the same "batch" are bright orange. What's always puzzled me is what causes them to turn colors at all - they will go from dark to orange almost overnight, after staying dark for a year or more.

So many good questions!
 

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