The Aquarium Catfish website
https://planetcatfish.com/forum/
.
Jhelf12 wrote:This guy started to change color to yellow about 2 weeks ago.
NCE12940 wrote:Too early to tell with Sr. Paz. This is a fairly recent color change and I've only had him just short of a year.
The fact that your fishes change color for what sounds like weeks or months at a time says to me that this is a form of Morphological Color Change (long-term changes in essential body color which may or may not be reversible) rather than Physiological Color Change (e.g., rapidly occurring (and just as rapidly reversing) color changes, such as stress coloration, flash colors, etc.) If anyone is interested in a not-too-old article on the phenomenon of morphological color change in fishes, here is a good read:jodilynn wrote:Yes the color on my females goes back to "normal", the varying amounts of yellow come and go. Right now they are both back to being dark, i.e. my Green Dragon is a dark olive with yellow edging on her tail and my Lemondrop is dark brown with yellow spots and yellow on her tail.
Eric Leclercq, John F Taylor, & Hervé Migaud wrote:ABSTRACT: Morphological skin colour change in fish is often referred to in the sole context of background adaptation. It is becoming increasingly apparent that it is a broad phenomenon elicited by a variety of factors. To date, no review has attempted to integrate the different types of morphological colour changes occurring in teleosts, their ecological origins and the regulatory mechanisms involved, often restricting the view on the subject. First, the origin of skin colour is addressed in teleosts including chromatophore type and distribution, pigment biosynthetic pathways and their interactions to one-another. Second, the different types of morphological colour changes occurring in teleosts are categorized and a key distinction is made between proximate and ultimate morphological colour changes. These are defined respectively as the change of phenotype during an established life-stage in response to environmental interactions and during the transition between two developmental-stages phenotypically pre-adapted to their ancestral ecosystems. Nutrition and UV-light are primary factors of proximate morphological colour changes beyond the control of the organism. By contrast, background light conditions and social interactions are secondary proximate factors acting through the control of the organism. Highly diversified among teleosts, ultimate morphological skin colour changes are presented in term of alterations in skin structure and pigment deposition during metamorphosis in different species. Finally, the physiological and endocrine mechanisms regulating both proximate and ultimate morphological colour changes are reviewed.
I was able to download both of these articles at home (not at school), so they should be free to download (although the first article can only be obtained from the second link, "Researchgate," which is not the publisher's site).Helen Nilsson Sköld, Sara Aspengren, & Margareta Wallin wrote:ABSTRACT: Physiological color change is important for background matching, thermoregulation as well as signaling and is in
vertebrates mediated by synchronous intracellular transport of pigmented organelles in chromatophores. We
describe functions of and animal situations where color change occurs. A summary of endogenous and external
factors that regulate this color change in fish and amphibians is provided, with special emphasis on extracellular
stimuli. We describe not only color change in skin, but also highlight studies on color change that occurs using
chromatophores in other areas such as iris and on the inside of the body. In addition, we discuss the growing
field that applies melanophores and skin color in toxicology and as biosensors, and point out research areas with
future potential.