[mjwgh2]

It is well-documented that certain black pigment patterns in the many species of Xiphophorines (platies and swordtails) can produce melanoma cancers in hybrids. I have seen melanomas on individuals of the "bumblebee" strain and I expect that is is eventually fatal as in other affected hybrids. Most of the commercially produced swords & platies are complex hybrids originally produced from inter-species crosses. Cancers are not unknown in black spotted hybrids. Here is a link to an historical article by Myron Gordon with an extensive bibliography, containing references to production of melanoma in these fishes.

https://gato-docs.its.txst.edu/jcr:578c6df2-9600-49c5-a90a-a7bf072c7962/HowtheXiphophorusProblemArrivedinSanMarcos.pdf

 

[Ophidian]

Oh dear. Thank you for confirming my suspicions. I’ll keep a close eye on her with the knowledge that I may eventually need to make a quality of life decision.