Personally, I think that the name 'Betta sp. cf. rutilans green' is something of a misnomer. Having kept both these, and the more common Betta rutilans, I believe Betta sp. cf. rutilans green is an entirely distinct species. The difference in not only appearance, but also reproductive methods (mouthbrooding as opposed to bubblenesting), does leave me confused as to why the two seem to currently be considered under the same species banner.
All that aside, readers of this site, will know that I keep a group of this species. These are the offspring of my original pair, which were purchased back in 2011. Currently, I also have a small group of F2 fry, the result of spawning a sibling pair. This is something of an impressive feat, when you consider these fish are upwards of two years - with some individuals now closer to three!
At present, I keep the F1 fish in a 40L tank. Like all members of this complex, they are not a large fish, with mature males measuring around 5cm total length. With that said, these are perhaps the most violent bettas I have owned to date. The males are highly aggressive towards each other - a situation that seems to have only worsened over time.
The original family group, including the F0 pair and about a dozen sub-adult and adult offspring, cohabitated without much issue in a 40L tank. Really, it was not until the original pair died and the F1 males started to reach sexual maturity, that I had problems.
It didn't help that the group have had to spend weeks at a time in a dark, sparsely decorated hospital tank, being treated for a virulent oodinium infection. Not only did this greatly increase stress levels, but the death of several individuals during treatment, seemed to throw the whole group into an orgy of violence. The male in the photo below, is showing relatively minor fin damage. The worst injuries are those done to the gill and head area. Right now, I have a male with one of his operculum almost completely torn off. Another, has a large wound on his head, where the skin underneath is showing through.
I have tried everything I know to decrease aggression. But no matter the size of the tank or density of cover provided, there's been no change. I don't know why it is that the males in this group are so excessively violent, but with an increase in the severity of injuries, and the frequency with which they are occurring, I have decided my only option is to physically separate them.
The plan is to set-up one of my empty 60x30x36cm tanks. The males will be housed in 2L soda bottles (or a container of a similar size), which will be fastened to the inside of the tank with suction caps. These soda bottles will contain a few sprigs of either hydrilla or watersprite to help with water quality, and the water will be kept tinted with IAL. Females will be kept together in the main part of the tank. Unfortunately, space restrictions mean this is the only way I can jar out my males but also keep them warm. Otherwise, I would have removed them from the tank entirely, and given them each larger lodgings.
So if anyone wondered why I so rarely share photos of my Betta sp. cf. rutilans green group compared to my other fish, it is only because in their present condition they don't make for particularly attractive subjects. Hopefully, once given the space to recover, I will be able to provide some more up-to-date photos (the photos in this entry are from earlier this year).
Hailing from Melbourne, Australia, I currently keep and breed a number of species from the coccina complex.