Are women not as interested in the hobby, or could they just be less likely to join forums and competitions as so keep a lower profile …
Some of my other hobbies seem very male dominated as well (bonsai, ponding) and I often wonder why. However, at in-person club meetings the ratio evens out. Koi ponding is usually a husband/wife endeavour but often it is the husband who uses the forum.
For bonsai, and indeed aquascaping, you would think more women would be the norm - it seems to be true for other types of gardening and plant related activities. I think more often than not it is mothers who set up fish tanks for their kids, rather than dad’s. I know I often used my kids as an excuse to get more animals including aquariums, citing educational purposes, when I really just wanted them for myself … lol!