Marbles are beautiful when they’re young, but are at high risk of developing tumours, especially if they have white scaling like my two babes did.
The first pictures show them tumour-free and then the second shows them with tumours. In both cases, the tumours started developing within the first few months of being home.
The female featured in the bottom set had to be humanely euthanized because the tumours on her back and peduncle eventually caused her to be unable to swim. This led to lethargy and loss of appetite, so I had to let her go.
The male featured above, currently still living at the time of writing this, is now experiencing lethargy. He had to be rehomed earlier the year due to a major move, and the new owner has let me know that the tumours he previously had are growing faster and bigger. It’s on his back and both sides. They’re trying some things to make him comfortable, but know that humane euthanasia may be required.
Marbles, just like true dragonscale and metallic bettas, are at higher risk of developing tumours than other varieties. You also see increased risk in “monster” bettas (typically blue bettas with a white face) and “koi” bettas (both monsters and kois are still marble bettas). “Fancy” bettas also tend to be marbles, but seem to usually be labelled this when they have more orangey and blue/green colours.
It’s interesting to note that I’ve seen tumour or cyst-like protrusions on two of my other bettas in the past as well, but they never developed as aggressively or in the same manner as those on the marbles:
It’s also interesting to note that in the two cases above, the protrusions both look similar in appearance and are on the same area of the body. In the red male above, he was dealing with a viral infection that had a host of other symptoms; the female, still currently living at the time of writing this, also seems to be dealing with – what I believe to be – a bacterial infection, given the condition of her fins as well. (She was rehomed along with the male marble above, so this picture was sent to me by the new owner.)
With marbles, tumours are believed to be caused by overactivity of iridophores; in the red veiltail and dumbo female, it seemed to stem from internal infections.
So, although I meant this to be a post about marbles, it also kind of turned into a tumour post as well, hah.
Anyway, that’s just my musings and also general warning about buying marbles. More and more these days, it seems like tumours are becoming common across bettas of all types and ages, anyway, so be vigilant.