Why Do Goldfish Change Color in Outdoor Ponds?

It's completely normal for goldfish to change color over the course of their lifetime. While not generally an indication of poor health or harmful environment, the color change may cause concern among fish owners. Several factors can contribute to color changes in outdoor, pond-inhabiting goldfish.

  1. The Facts

    • According to the Goldfish and Aquarium Board, biologists identify two types of color change in fish: physiological and morphological. Physiological change occurs when certain organelles within a pigment cell spread throughout the entire cell, making the pigment (color) more visible to the naked eye. If these organelles gather at the center of the cell, the pigment is more muted.

      Morphological change occurs when the fish gains or loses pigment cells. Acquiring more cells of a specific pigment will enhance the color, while losing cells of a specific pigment will diminish that color.

    Genetics

    • Depending on their genes, some goldfish will change color over time in the same way that humans' hair color changes. The parents' genetic makeup affects this, as will the way the fishes' bodies respond to their environment, according to GoldfishConnection.com.

    Significance

    • In their first few months of life, goldfish will most likely change color quite drastically as part of their natural development, reports AmericanGoldfish.org. While possible later in life, color change generally appears most often in the early years.

    Influences

    • Light--an essential part of good health for goldfish--contributes to a favorable appearance as well. Ultraviolet (UVA and UVB) rays from natural sunlight can enhance goldfish color. Proper indoor lighting also has an effect, but the sun tends to increase the vibrancy even more, the Goldfish and Aquarium Board states.

    Considerations

    • A goldfish's body color suddenly going from bright to dull may indicate a serious illness. This can happen if the fish has a parasite or bacterial infection. Alterations in chemicals, such as pH and ammonia, can also dull color. Another possibility, according to GoldfishConnection.com, is that an antibiotic regimen has harmed necessary bacteria in the fish's system.

    Warning

    • Like humans, goldfish respond to stress physically. Stressful situations can include living with predatory fish, improper pond conditions, or injury. Goldfish, when new to a pond, often show black spots on their bodies. Such marks merely indicate bruises from being moved to a new home, and will disappear with time, GoldfishConnection.com reports.

    Expert Insight

    • The Goldfish and Aquarium Board states that goldfish that live in a pond have a greater likelihood of eating a natural diet of plants, insects and algae. These foods provide nutrition that can optimize color. While you can raise a healthy fish on store-bought food, the diet in a pond will support ideal coloration.