What happens when a goldfish doesn’t have access to sunlight?
If you leave your goldfish out of the sun for a long period of time, yes they will begin to lose that lovely orange/red colour, in exchange for a paler colour. If your goldfish is kept in the dark at night, you may notice it appears a little paler when you turn the lights on in the morning. Goldfish kept indoors without full-spectrum lighting are also less-brightly coloured than the fish that are exposed to any natural lighting outside. If you keep your fish in the dark all the time, the chromatophores wont produce more pigment, so the fish’s colour will start to fade as the chromatophores that already have colour naturally die, while the new aren’t stimulated to produce any more pigment. However, your goldfish wont become white if you keep it in the dark because fish also get some of their colouration from the foods they eat. Many fish foods contain canthaxanthin, a pigment which enhances fish colour.
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