Angelfish are one of the universally kept freshwater aquarium fish, also the generally kept cichlid. Their beauty lies in their spectacular fins and impresses many with their strips which are of varied colors. These stripes are maintained constantly by width and space as the fish grows. Iridescent blues and greens of halfback and tiger like black stripes are the few spices of angelfish. Some have more orange color resembling to be like a sunrise on their body. These stripes obtain a variety of colors due to pigmentation or because of interactions of light with various compounds. The collective effects are really outstanding.
There are many fascinating observations about angelfish stripes patterns. The bars on them appear as of zebras and silvers with a number of patterns and shapes. These stripes vary in intensity and sometimes fade away completely within a blink of time.
Once we get into the details of these patterns and study the sub-cellular terminology, we can see that the fading of stripes happens due to angelfish integumentary cells. Dermis and epidermis are the two layers of fish’s skin. In dermis pigment containing skin cells called chromatophores which help in the development of scales within the fish. It is the layer deep to the scales and has the attributes of light-reflective cells called iridophores. These produce iridescence on fish and in combination with chromatophores produce a variety of colors on the fish’s skin. For example, Melanophores restrain black-brownish tincture called melanins, which is responsible for the dark color patterns on the fish body. It has also got the quality to fade away with specific movements of the melanosomes within each pigment cell.
Stress level in fish promotes to change the intensity in patterns at a greater scale. Dark, distinct stripes are found on a calm fish and when the same fish exposed to a bright light, which indirectly causes certain stress on the fish and fades away the stripes. This tells us about the control system of sympathetic nervous system in their body.
The main reason here is – the distribution of melanosomes throughout the melanophores causes the dark pigmentation to disappear and decrease the intensity of stripes. This also results in the change of size and shape of an angelfish.
These pattern intensity changes occur due to natural phenomenon within an angel and are observed temporarily. Conversely, the faded shade in the fish’s stripes also appear due to any weakness or unhealthy conditions which arise due to uncomfortable environment or while suffering from any disease. However, this may result to a permanent fade of stripes pattern on the fish.
I hope this will help today’s angelfish keepers to improve their skills to maintain angelfish properly. Remember, an angelfish when fell secure and healthy would decrease their stress levels. This can be achieved by placing them in aquariums which are having dark bottoms, or one with less light sources and good decorations.