Long time no update!
The fish are still going well. The muscles are quite happy (or seem it) and are still alive and move around quite a bit when the lights are out. Plants are doing well too, and I've even managed to grow Ech. Amazonicus in the cold water. Cabomba grows in there too, but that's not a surprise really.
The plant floating at the top is Cardamine. It grows out of control in my planted tank, so I remove a pile and put it in the goldfish tank.