Do Neon Tetras Lose Color at Night?

Aquariums are nowadays a standard part of residential and commercial properties. They introduce a touch of color and sophistication into indoor spaces without the high price tags of most decoration options.

by Fabian

Updated: June 22, 2020 / 5 mins read

Fabian is the dedicated Chief Editor at Aquarium Nexus. From a young age, he was captivated by the vibrant world of aquatic life, leading him to accumulate over 20 years of experience in keeping and breeding various fish species. The fulfillment derived from the aquarium hobby has remained a constant throughout Fabian's life. As an expert in the field, he finds great pleasure in imparting his extensive knowledge and personal experiences to both seasoned aficionados and budding enthusiasts.

Even so, this will only be possible with the right fish species in the tank. One of your best choices is the neon tetra. This is considered an aquarium’s crowning glory owing to its exquisite beauty.

It has a blue-green iridescent stripe running to the caudal peduncle from its iris and a broad red line from its tail to the dorsal fin. These colors combine to give your aquarium a perfect look.

One thing that most aquarists will worry about when keeping neon tetras is their loss of color mostly in the dark. Other people will report a fading of the color rather than its loss in the dark.

A few aquarists erroneously assume that this color loss is a figment of their imagination and will choose to ignore it altogether. At night and, sometimes, in reduced lighting, the neon tetras will adopt an inconspicuous color and this is normal.

With the tidbits below, you will understand what causes these color changes in neon tetras. You can then know what to expect and put your worries aside when rearing these fish in your tank.

Why Do Neon Tetras Lose Their Color?

The color changes in neon tetras are associated with several crucial functions, including camouflage, protection from UV radiation and sexual selection.

Generally, the color of your fish is linked to optical interference and the absorption of light rays by chromatophores. Chromatophores are the cells that determine the skin color of basal vertebrates like the neon tetra.

These cells are subdivided into those that reflect light rays (structural) and those that absorb the rays (pigmentary).

Pigmentary chromatophores are further classified into erythrophores (orange/red), melanophores (brown/black), cynaphores (blue) and xanthophores (yellow). The structural chromatopheres have no biochromes and have iridescent and silver hues.

The skin color of neon tetras arises from a combination of the light transfer mechanisms of the fish’s chromatophores. These include iridescence, fluorescence, refraction and reflection. The color changes to the fish can be morphological or physiological. 

The physiological change is attributed to the movements of the membranous vesicles that contain color in pigmentary chromatophores. The color change in structural chromatophores occurs due to small alterations in the distances between the lamellae of their nanostructures.

Physiological color change in tetra fish occurs within seconds to hours based on the fish’s exposure to light. After a few minutes of darkness, the cytoplasm layers of the chromatophores expand and part, making the fish become a dull violet-blue.

When exposed to light, the layers come together, and the fish becomes a brilliant blue-green as the fish’s energy levels increase.

Morphological color changes in neon tetras, on the other hand, take place over several days or weeks. They are the result of alterations in the density of the pigment amount in the chromatophores’ cytoplasms. In most instances, this change happens in disease.

Do All Tetras Lose Their Color At Night?

Though the color fade in neon tetras is normal, not all fish will lose their colors at night. This is because different fish will sleep at varying times and have variable levels of rest.

The intensity of the color loss in neon tetras will also depend on an individual fish. Some neon tetras will retain some of their vibrancy in darkness, and this is also normal. Take time to study the mannerisms of your fish, so you know what to expect.

Do Neon Tetras Need Light At Night?

Neon tetras need 12-14 hours of lighting to maintain the right circadian rhythm. They thus need no light in their tanks at night.

The best choice is to put a timer that automatically switches your tank’s lighting so that your fish will settle into a routine.

Moreover, neon tetras are used to subdued lighting in their shady natural environment. Bright light in your aquarium at night might stress your fish and affect their rest.

Focus on getting the precise lighting preferences for your neon tetra. A low-watt fluorescent bulb of between 18-40 watts will suffice for the 12-14 hours of lighting.

You can, however, settle for a 2-5-watt bulb for each gallon of water in a planted tank.

Do Tetras Lose Color When Stressed?

In most cases, stress for tetras is attributed to the wrong water parameters. Neon tetras are quite sensitive to water changes. They are among the best indicators of the water quality in your aquarium.

Even the smallest derangements of water parameters can leave your fish stressed. The stress, in turn, causes the loss of color in your fish. This is probably because the fish’s energy levels are drained, or they are not as active as they should be and their chromatophores, therefore, part.

Other than deranged water parameters, neon tetras can become stressed by the wrong tank mates. The ideal tankmates for tetras include peaceful barbs, small catfish and small rasboras.

Cichlids, betta fish and angelfish are aggressive tank mates that might be inclined to eat the tetra because it is a small fish.

As such, your tetra will spend most of its time hiding and inactive, and lose color. Neon tetras are shoaling fish and not keeping them in groups can also cause the one you have to become stressed.

Wrapping Up

Most people assume that a neon tetra is on its deathbed when it loses color. Even so, these tidbits have enlightened you on what a loss of color in your tetra could indicate and when you should be worried.

Aim to maintain a clean tank with balanced water parameters and lighting and include the right tankmates for your fish to exude a vibrant color during the day.

You can then sit back and admire the bright colors of the tetras and see your stress levels decrease while brightening your space.