What background colour for an aquarium? What a goldfish study measured
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
The tank's background — the card or sticker on the back wall — is usually chosen for how the whole setup looks. A goldfish study shows it also weighs on the fish's own physiology, an angle we had not yet covered in our fish toys and enrichment section.
Contents · 5 sections
Four colours, eight weeks
Published in 2015 in Aquaculture Research by Eslamloo, Akhavan, Eslamifar and Henry, this study raised goldfish (Carassius auratus) for eight weeks in tanks with a white, black, blue or red background (, doi 10.1111/are.12177). The researchers tracked growth, skin pigmentation, several immune markers and plasma cortisol in each group.
White and black ahead on growth and immunity
Growth performance rose markedly more on a white background than under the other three conditions. Two innate immune markers, lysozyme and antiprotease activity, more than doubled in fish raised against a white or black background compared with those raised against blue or red — a sign of stronger natural defence against pathogens rather than a purely cosmetic detail.
Red, the colour that raised cortisol the most
Plasma cortisol was significantly higher in fish kept against a red background than in those kept against black or white. Blue did not show the same marked rise, but it still trailed white and black on the immune markers. A red background, often chosen for the visual contrast it gives a red or orange fish, comes out as the least favourable of the four conditions across the measured criteria.
A finding, not a universal rule
This result holds for goldfish under the tested conditions: other studies on other aquarium or aquaculture species find different, sometimes opposite, optimal background colours, which suggests an effect tied to each species' own biology rather than one universally calming colour. For goldfish specifically, this result adds to what we cover on their diet and colouration and on enrichment suited to the species.
Frequently asked questions
Should a red or orange background be avoided altogether for goldfish?
It is not a ban, but a white or black background clearly comes out more favourable in this study on the growth and immunity criteria measured, without a red background being shown dangerous in the short term.
Does this result apply to other aquarium fish?
Not directly: the study covers only goldfish, and the literature on other species shows different optimal background colours depending on the case.
An accessory from our shop for this use: Tall artificial aquarium plant, 45 to 49 cm, weighted base (€23.90) · the whole shop
This guide is part of Planète Pets’s Fishkeeping universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.