Little update here, the few fry that remained are currently doing well. This is the largest of them (in the plastic box) next to an adult female for comparison. They are eating brine shrimp nicely and I also offer some banana worms for the slower growers. Note that this is ~2.5 months old and is still quite small! Probably keeping the temperature in the tank around 25C (during the winter) is also a reason for their slow development, so the next rearing attempt will be in the summer time, when the temperature in the tank reaches 28.5C (and is kept there with cooling fans).